Soft water exists wherever water is flowing across terrain that is poor in soluble minerals. The rivers of South America, Southeast Asia and West Africa are predominantly rivers of this type. Because so many of the ornamental fish sold in the trade come from these areas, many hobbyists assume that they need or prefer soft water conditions in the aquarium. Up to a point this is indeed the case, but creating and maintaining a soft water aquarium places an extra set of challenges on the aquarist. These are as follows:

1. Soft water exhibits a stronger tendency towards pH instability than hard water. All aquaria become more acidic over time, but in soft water aquaria this trend can be very rapid. Since few fish will tolerate rapid changes in pH, frequent pH tests and the use of chemical buffers are an important aspect of maintaining a soft water aquarium.

2. If you don’t have soft water on tap, turning hard water into soft water is expensive. Reverse-osmosis filters provide soft water, but at a price. Collecting rainwater is a practically zero-cost alternative, but it is not without problems of its own.

3. Domestic water softeners do not produce soft water usable in an aquarium. All they do is replace limescale-forming minerals with minerals that don’t form limescale. This is fine for washing machines and dishwashers, but bad for fish tanks.

4. Filter bacteria work best in hard, alkaline water conditions. In very soft and acidic water, filter bacteria may not work at all, forcing the aquarist to use less efficient methods of filtration, such as the use of zeolite.

5. Not all livestock will do well in soft water conditions. Most notably, the livebearers or Central America will not do well in soft water aquaria and will be plagued with problems such as fungal infections and finrot.

Preamble: Why Bother?

One of the paradoxes in freshwater fishkeeping is that while most fish naturally from soft water environments will thrive in hard water aquaria, the reverse is almost universally not true. Tetras, Barbs, Gouramis, Corydoras catfish and Angelfish are all examples of originally soft water fish that are routinely and successfully kept in hard water community tanks. But Livebearers, Central American cichlids and Rift Valley cichlids almost never adapt to soft and acidic water conditions. In other words, if all you want is a mixed community tank, then hard and alkaline water will allow you to mix Platies, Neons and Corydoras without problems.

So why bother with soft water aquaria at all? Soft water becomes useful in one of two situations.

In the first place, soft water may be critical to breeding a certain fish. While tetras and South American dwarf cichlids will live quite happily in a hard water aquarium, they will not spawn. Sometimes they will deposit their eggs willingly enough, but because of the improper water chemistry, the eggs will not develop. In other instances they simply won’t exhibit any breeding behaviours at all. For aquarists maintaining community tanks this isn’t an issue, but for hobbyists wanting to breed these fish, then transferring them to a soft water aquarium becomes essential.

The second situation where a soft water aquarium becomes important is when certain delicate fish are being kept that cannot adapt to hard water. These tend to be species kept by advanced hobbyists, including things like wild-caught Discus and Apistogramma, certain Rasboras, and some of the more demanding Gouramis such as Chocolate Gouramis.

Precaution: Acidification

Before looking at how to set up a soft water aquarium, it is essential to first explain the problem of acidification. All aquaria have a tendency to become more acidic over time. Acidification is caused by four main things:

1. Nitrification. Filter bacteria convert ammonia excreted by fish and from decaying organic matter into nitrite first and then nitrate. Nitrate forms nitric acid, and this in turn lowers the pH. In most freshwater aquaria, there is not active removal of nitrate (or nitric acid) through denitrification, because the anaerobic conditions required tend not to be favoured by freshwater aquarists. Photosynthesising plants will of course remove some nitrate, which they use as a nitrogen source for protein synthesis, but except in heavily planted aquaria this effect is usually trivial.

2. Respiration. As organisms respire they produce carbon dioxide, including the fish, plants and filter bacteria. The carbon dioxide dissolves in the water to form carbonic acid, the same stuff that makes soda pop acidic. To some degree vigourous aeration will release the carbon dioxide into the atmosphere, but a heavily stocked tank will still experience more rapid acidification than a lightly stocked one.

3. Photosynthesis. The effect of plants on pH is complex because aquatic plants use two different sources of carbon, dissolved carbon dioxide and bicarbonate ions. Dissolved carbon dioxide forms carbonic acid, which lowers pH. As plants photosynthesise, they remove this carbonic acid, allowing pH to rise. However, in most aquaria the actual concentration of carbon dioxide in the water is very low, which is why aquarists concerned with plant growth need to fertilise their tanks with addition carbon dioxide. If there is insufficient carbon dioxide for their needs, plants will switch to using up bicarbonate ions. Bicarbonate ions are a major part of the alkalinity reserve in the water, that is, the ability of the water to resist changes in pH. With the bicarbonate ions taken away, the water loses some of its buffering capacity, and the pH drops. The overall result is that rapid plant growth coupled with insufficient carbon dioxide and/or bicarbonate concentration can lead to dangerously fast acidification.

4. Bogwood and peat. Though often overlooked, bogwood can be a significant source of acidity. This is especially true where the bogwood has not been fully cured. The acids produced by bogwood are predominantly tannins. Peat also effects water in a similar way. If peat is used as a substrate (as is sometimes done with killifish) the water will become more acidic.

While all aquaria will be subject to some or all of these factors, not all aquaria react in the same way. A critical difference between those tanks that become acidic rapidly and those that do not is the alkalinity reserve. Hard water (whether fresh, brackish or marine) contains an abundance of mineral ions, in particular carbonate and bicarbonate ions. These form the alkalinity reserve. Any acids produced within the aquarium will be neutralised by the carbonate and bicarbonate ions.

In hard water aquaria, the alkalinity reserve outweighs potential sources of acidity

Soft water aquaria are different. By definition, soft water contains few dissolved minerals, and as a consequence the alkalinity reserve is very low. There’s nothing much in soft water to mop up acidic chemicals, so these will accumulate and lower the pH between water changes. In other words, soft water aquaria are subject to faster and more severe drops in pH than hard water aquaria.

In soft water aquaria, insufficient alkalinity allows rapid acidification

The problem is that fish do not like rapid changes in pH. When pH changes, fish will adjust the chemistry of their blood to prevent physiological problems. But having to constantly alter their blood chemistry is stressful. It is therefore important that as well as providing a suitable pH for the fish being kept, the aquarist keeps that pH steady. Moreover, once the pH drops below 6.0, fish not otherwise adapted to strongly acidic conditions will suffer from acidosis. This results in damage to the gills and skin, problems with respiration, and eventually death. Below pH 6.0 the bacteria in a biological filter essentially stop working, leading to potential ammonia poisoning. Even for those fish tolerant of acidic conditions, the sudden rise in ammonia can be lethal.

Setting up a soft water aquarium

Obviously calcareous materials such as seashells and tufa rock cannot be used in a soft water aquarium. These will dissolve and raise the hardness and pH.

It is also important to avoid using anything that promotes acidification. As a general rule, the soft water aquarium needs to be as chemically inert as possible, containing nothing that will either raise or lower the pH and hardness. Bogwood, peat and coconut shells are best left out of the soft water tank because they produce tannins and remove hardness. To avoid problems with carbonic acid, understock the tank and use aeration do drive the carbon dioxide into the air. Likewise nitric acid is best managed through understocking the tank, feeding the fish only sparingly, and performing regular water changes to dilute the nitrate. While plants can be used in the soft water aquarium, it isn’t a good idea to use large quantities of rapidly growing species, particularly species that extract bicarbonate from the water.

One way to avoid problems with acidification is to ensure that there is a modest alkalinity reserve in the water, and then to use substantial water changes to replenish it every week. Unless you are keeping species that need very soft water, moderately soft water conditions will suit most Tetras, Rasboras, Apistogramma and Discus. Aim for a hardness between 5-10˚ dH and a pH around 6.5.

Alternatively, you can use a pH buffer to stabilise water chemistry. A chemical buffer neutralises chemicals that threaten to raise or lower the pH. Used properly, they can be very effective and dramatically improve the stability of the aquarium. The commercial chemical buffers offered to aquarists typically contain phosphoric acid, and stabilise the pH around 6.5.

The value of pH buffering products is often misunderstood. Adding a buffering product that slightly acidifies the water doesn’t turn hard water into soft water. Neither will fish that need soft water be satisfied with hard water that has been acidified using a chemical buffer. The value of a buffer is in making soft water stable; nothing more, nothing less.

Filtration can be a problem. Filter bacteria work best at around pH 7.0, and as the pH drops, their performance sharply decreases. Below pH 6.0, filter bacteria are hardly working at all. Chemical filter media that remove ammonia directly (such as zeolite) are the only option in such aquaria. Because chemical filter media need to be replaced or recharged, regular water testing and routine filter maintenance are essential. The idea is to change the filter media before ammonia is detectable — not afterwards!

Making soft water

If you live in a soft water area you may have water of appropriate pH and hardness for a soft water aquarium. Maintenance of the aquarium will be relatively straightforward because you can perform large and regular water changes, and thereby minimise any problems with water quality of acidification.

For aquarists in hard water areas things are more complicated. Soft water needs to be made up by mixing a small proportion of hard water with a larger proportion of pure water. This will dilute the hardness in the tap water resulting in something with a pH and hardness level useful for soft water fishkeeping. There are two main sources of pure water: reverse-osmosis (or RO) filters, and rainwater. Each source has its pros and cons.

RO water is convenient because you can produce pure water as required. RO filters come in different sizes scaled to the demands of different fishkeepers. However, RO filters are expensive to buy and certain components may need replacing at intervals. RO filters are also rather wasteful, with about 10 litres of tap water being discharged for every 1 litre of pure water produced.

Setting up a rainwater butt to collect water from the gutters on your home is easy to do and the equipment very inexpensive. Obviously the rain itself costs nothing. The downside to rainwater use is that it depends on regular rainfall, something not all aquarists can rely upon. It is also important to store a certain amount of water to allow for water changes during dry spells. The risk of air pollution contaminating rainwater is pretty trivial, and simple filtration through carbon will remove most potential pollutants anyway. Detritus on the roof and in the gutters is more of a problem. While decaying leaves and drowned insects don’t really harm the fish directly, they can contribute to acidification, and they are certainly unsightly. Regular cleaning of the entire system is therefore an essential and tedious chore, and a net should be used to sweep up any detritus in the rainwater before use.

Pearson’s Square

To calculate the ratio of pure water to hard water required to make soft water of a given hardness you need to use a Pearson’s Square. The diagram below shows how this works. In this example shown, the ratio of tap water to pure water is 5 parts to 15 parts, i.e., one part tap water to every three parts pure water. Alternatively, you can use tools like my freebie program Soft Water Ware to do these calculations for you.

Pearson’s Square is quick way to calculate the proportion of hard water and pure water to create soft water of required hardness

Additives

Because soft water is poor in minerals, various trace elements supplements are produced for aquarists keeping soft water aquaria. These supposedly help the health of the fish, and are simply added to each new batch of water. Whether or not they are useful will depend on how soft the water is that you are using. If you are mixing pure water with hard water to create something around the 5-10˚ dH mark suggested, there is unlikely to be any shortfall in the amount of these trace elements available. But if you are keeping your fish in water that is softer than this, then adding mineral supplements may make sense.

Some blackwater extracts also include trace element supplements and are intended to be used in the same way. The value of blackwater extract is often misunderstood by inexperienced aquarists. Adding blackwater extract to a hard water aquarium doesn’t turn it into a soft water aquarium. Blackwater extract by itself merely changes the colour of the water. It’s a cosmetic effect, and while safe to use and visually attractive, shouldn’t be mistaken as a tool for keeping fish that need a genuinely soft water aquarium.

Peat filtration

Peat used to be a very popular way to soften and acidify water for use in aquaria. It has largely fallen out of favour, particular since the advent of RO filters. Peat acts as an ion exchange resin, remove minerals from the water and replacing them with organic acids known as humic acids. Besides softening the water, peat turns the water dark brown in much the same way as blackwater extract.

The main problem with peat is that it isn’t completely predictable. Adding peat directly to the aquarium (for example inside a canister filter) will soften and acidify water over time, but the rate at which it operates will depend on the original hardness of the water. Water that is very hard may not change very much at all, while water with relatively low hardness can become acidic so rapidly the fish are stressed.

The safest and simplest approach is therefore to use peat to treat water before adding it to the aquarium. Peat is placed inside a box or canister filter, and that filter placed in a container of water. As the water is passed through the filter, the peat will reduce the hardness and lower the pH. Once the water has reached its desired hardness and acidity, it can be used in your soft water aquarium. This may take many days though, even weeks, depending on how hard the water was to begin with and how much peat you are using. So you will need to experiment a bit to get a system that produces enough water to meet your demands.

Not an option: Domestic water softeners

Contrary to their name, domestic water softeners do not make soft water usable in aquaria. What they do is produce water that doesn’t contain the temporary hardness that furs up pipes. They do this by replacing the temporary hardness minerals with other types of minerals, typically sodium salts. Water from a domestic water softener is not really suitable for use in any aquarium, let alone a soft water aquarium.

Closing remarks

The soft water aquarium presents both opportunities and hazards to the fishkeeper. On the plus side, there’s no doubt that some of the real jewels of the freshwater side of the hobby — including Apistogramma, Harlequin Rasboras, Cardinal Tetras and African Killifish — never look better than when kept in soft, acidic water stained the colour of tea. Under such conditions these fish truly rival mbuna and coral reef fish in their beauty, whereas when kept in hard water their colours are often lacklustre and muted.

But the soft water aquarium is categorically not easy to set up or maintain. Besides the problem of making soft water if you don’t have it on tap, there are serious issues with acidification and management of the nitrogen cycle. Neglecting these issues will quickly lead to disaster.

Family: Aplocheilidae

Distribution: Sierra Leone, Guinea, Liberia. It is found in coastal swamps.

Maximum standard length: 1.5″ (3.75cm)

Minimum tank size: 45 x 25 x 25 cm – 28 litres, although it can be spawned in smaller aquaria.

Tank setup: A dark substrate should be used, ideally peat moss or the like (though the use of peat is not essential) and the tank should have dense areas of planting and pieces of wood to serve as cover. The use of floating plants is also recommended, as the fish love to hover beneath these. This species is an accomplished jumper, so the cover must be very tight fitting. The aquarium should be exposed to several hours of bright light daily as this seems to intensify the colour of the fish.

Temperature: 24-26°C

Ph range: 5.0-7.0

Hardness: 2-12 dH

Diet: Small live or frozen foods such as daphnia or bloodworm should form the basis of the diet. Dried foods may be accepted.

Compatibility: Pseudepiplatys annulatus can be kept in a community setup, provided tankmates are chosen with care. This is a very peaceful, shy species and will easily be outcompeted by more vigorous fish. Ideal choices include small characins, rasboras and dwarf cichlids, Corydoras, small Loricariids and possibly other small, peaceful killis.

Sexual dimorphism: The male is the larger, more brightly coloured fish with longer caudal, dorsal and anal fins.

Breeding: Not easy. Egg hanger. A spawning tank should be set up containing soft, acidic water of around pH 5.5 and a temperature of 79-82°F. Slight deviation from these parameters is acceptable.

The spawning aquarium should be dimly lit, with floating plants for cover. Large amounts of spawning medium in the form of fine-leaved plants such as java moss or nylon spawning mops should be provided. Peat filtration is beneficial. No substrate is necessary and gentle filtration via a small air-driven sponge filter is sufficient.

The fish should be conditioned in a separate aquarium with lots of live food before a trio comprising 1 male and 2 females is selected and placed in the spawning tank. The group will spawn daily, depositing eggs every 24 hours for around 2 weeks and these should be removed gently as they are noticed. In our opinion each trio should only be allowed to spawn for a week or so before being returned to the conditioning tanks. The spawning process is hard on the fish (particularly the females) and they can become fatigued and weak if left for too long.

The eggs should be transferred daily to a small aquarium or dish containing water from the spawning tank, to a depth of 1-2 inches. 1-3 drops of methylene blue should be added to this, depending on volume. This container should be checked daily for fungussed eggs, which should be removed with a pipette. The eggs will hatch in around 10-14 days, depending on temperature.

The fry are tiny and initial food should be infusoria. After a few days, they can be fed brine shrimp nauplii or microworm, with the introduction of larger and frozen varieties after two weeks or so. The water must initially be kept very shallow but the level can be raised as the fry grow. The fry are very delicate and tricky to raise and grow slowly.

The other method of breeding is to use a simple approach more often adopted with livebearing fish, but which works equally well for Pseudepiplatys annulatus. Simply plant a fairly large (say 80 litre) tank as heavily as possible, add a group of adult fish and let nature take its course! Obviously, the yield will not be as high as with the method outlined above, but some fry will survive and a viable population can be built up this way. Adult fish rarely consume fry.

NOTES: A truly stunning aquarium inhabitant, Pseudepiplatys annulatus is rare both in nature and the hobby and we urge anyone who obtains this fish to give breeding a go. It is often erroneously referred to by its former name of Epiplatys annulatus and is sometimes referred to by the common name of Rocket Panchax.

Unlike many other killifish species, it is usually found in bodies of permanent water and is not an annual species. Many different colour morphs exist, including yellow, red and blue forms.

Reproduction of this document by any means for commercial purposes requires the express written consent of the authors. Copyright 1996

Abstract

Experiments with planted aquaria appear to indicate that growth of green algae, red algae, and cyanobacteria is suppressed in planted tanks in which the availability of phosphate is the factor limiting plant growth. It is believed that when light, CO2, N, K, and all micronutrients and trace elements are present in slight excess relative to the amount of phosphate available for plant growth, certain higher plants are able to out-compete algae and cyanobacteria for the phosphate in the water column, starving them of this essential nutrient. Two case studies are presented as evidence for this hypothesis.
Introduction

There are few things as frustrating to the aquarist interested in growing aquatic plants as algae. After spending a small fortune on lights, substrate additives, liquid fertilizers, and CO2 systems in an attempt to get good plant growth, the aquarist is often rewarded with a lush carpet of algae. Unsightly and stubbornly resistant to eradication, the algae destroys the aesthetics of the tank while limiting plant growth by competing with them for light and nutrients.

In desperation, the aquarist experiments with various forms of algae control, including algicides, bleach dips, antibiotics (for cyanobacteria), physical removal, and the introduction of an assortment of algae-eating fish and invertebrates. Feed levels are reduced, light duration is decreased, and various combinations and amounts of fertilizer are tried, until through trial and error an uneasy truce is reached.

In the search for a solution, the aquarist is faced with an almost complete absence of information as to which of the many tank parameters should be altered in which order to eradicate algae already present while still maintaining favorable conditions for plant growth. This is hardly surprising given the huge number of variables, including light strength, duration, and spectrum; CO2, micronutrient, macronutrient, and trace element concentrations; fish load; plant and algal species and density; and water chemistry and temperature. Sometimes the information that does exist appears contradictory; in [1], excessive growth of cyanobacteria is attributed to high nitrite and nitrate levels, yet this pest is often seen in fully cycled aquariums with no measurable nitrite or nitrate at all.

One option available to aquarists with deep pockets is to follow the proprietary Dupla system [2], a system of liquid fertilizer drops, tablets, tap water conditioner, substrate additive, and undergravel heating coils. Magnificent planted aquaria are routinely produced this way, but the components are expensive, the ingredients are not disclosed on the package (but see [3]), and little insight is gained into the relationship between plants and algae (or how the system should be “tweaked” for best results).

Like many others, the authors attempted to grow aquatic plants using typical aquarium configurations and various commercial liquid fertilizers and substrate additives. Frustrated by their inability to attain results even remotely resembling the photographs in the literature, they began systematically to add specific nutrients to their tanks and record their observations. Although eradication of algae was not the immediate goal of the experiments, it was noted that once the aquarium water was supplemented on a daily basis with trace elements, micronutrients, and the macronutrients K and N but not P, not only did the plants begin to grow extremely well, algae of all types began to die off rapidly.

In this paper, case studies of the authors’ aquaria are presented. The case studies are followed by a discussion of the results in which a number of hypotheses are considered. These hypotheses are quite testable, and it is hoped that other hobbyists will be willing to perform controlled studies on their aquaria to either support or disprove them.
Case Study #1

Initial conditions as of November 1993: 500L aquarium with undergravel and canister filters; 240W fluorescent lighting, 12 hours per day; 15W UV sterilizer; 8cm 2mm gravel with a few laterite balls; no CO2 additions; no fertilizer; about 40 3-12cm fish; water temperature 27C, pH 7.5, GH 100ppm, NO3- 50ppm, 25% change every week; planted mainly with Hygrophila polysperma and Vallisneria gigantea, with a few Echinodorus sp., Cryptocoryne sp., and others.

The aquarium was purchased second-hand as a complete set-up and had been in operation at least six months prior to being acquired by the author [Conlin]. About a month after after being moved to the author’s residence, a dense coat of green algae developed on the gravel-coated glass-fiber backdrop. Plant growth was marginal, even for the H. polysperma, which had small 3cm leaves and was not spreading. Hygrophila difformis was introduced and promptly lost its lower leaves.

Change: Twenty Terrapur cones were embedded in the substrate and Sera liquid fertilizer was added as directed to the tank water during water changes. Hydrocotyle leucocephala was introduced.

Effect: Growth of H. polysperma, H. difformis, and V. gigantea improved but long strands of green thread algae started growing on the backdrop. Various Echinodorus and Cryptocorynes showed marginal growth. The H. leucocephala quickly degenerated, leaving a few small fragments growing at the surface. Some red algae was noted on the leaves of Anubias barteri var. nana and along the leaf margins of the V. gigantea. After a few months, blue-green algae (cyanobacteria) began to cover the gravel and some plants.

Change: Erythromycin sulfate was added to the water at approximately 3.2mg/L.

Effect: Cyanobacteria disappeared for several weeks but eventually returned.

Change: Less food (particularly frozen bloodworms) was offered to the fish and a DIY yeast CO2 system was connected to the tank.

Effect: Cyanobacteria remained. Nitrates were unmeasurable. Plant growth was noticeably faster. Depending on the state of the yeast reactor, tank pH varied from 6.8 to 7.5.

Change: The Sera fertilizer was eventually discontinued on the assumption that it was contributing to the growth of the cyanobacteria. It was replaced with a commercial iron-containing trace element mix (initially 1/8 tsp of powder a day, soon increased to 1/4 tsp a day).

Effect: Nitrates rose to about 20ppm. Green algae began to replace the blue-green algae on the plants and gravel. An iron test kit indicated the presence of iron at a concentration below the first level on the color chart (0.25ppm). Plant growth accelerated, but the leaves on the H. polysperma became bent and the lower leaves fell off. This was assumed to indicate a potassium deficiency [4].

Change: K2SO4 was added to the tank at the rate of about 1/4 tsp/day.

Effect: Shortly thereafter the nitrate level became unmeasurable, leading the author to conclude that nitrogen was now the factor limiting plant growth.

Change: KNO3 joined the list of fertilizers being added to the tank on a daily basis. To simplify dosing, the trace elements, K2SO4, and KNO3 were incorporated into a liquid fertilizer. The mixture was adjusted to keep the nitrates at about 10ppm when the enough liquid was added to the tank (about 12mL) to keep the iron at an estimated 0.1ppm.

Effect: At this point, growth of the H. polysperma, H. difformis, and V. gigantea became exceptional, requiring weekly trimming. Somewhere along the line, duckweed had been introduced to the tank and it now began to clog the surface. Cryptocorynes and Echinodorus began growing new leaves every few days and sending out runners. Algae of all sorts quickly declined to the point where careful observation was required to find it. Strangely, the Echinodorus were unusually pale in color despite iron fertilization. Magnesium deficiency was suspected.

Change: Epsom salts were added to the fertilizer mix.

Effect: Within a few days, new Echinodorus leaves showed normal coloration.

Change: The yeast CO2 system was upgraded to a constant-flow tank/regulator/needle valve system.

Effect: Reduced pH swings (6.8-7.0). More free time for the author.

Change: After several months, during which plant growth remained excellent and algae scarce, four pellets of “Vigoro Super Triple Phosphate 0-48-0″ (almost certainly Ca(H2PO4)2) were added to the tank as an experiment (approximately 0.1ppm phosphate).

Effect: The next day green spot algae was observed on the glass and Echinordorus leaves, followed two days later by blue-green algae that grew on some plants and driftwood. Duckweed soon required daily removal. Nitrates were unmeasurable several days after the phosphate was introduced but returned to 10ppm a week or so later (sadly, they weren’t measured just before adding the phosphate). Two weeks after the experiment began, the blue-green and green-spot algae began to decline, and duckweed growth returned to normal.

Current status: Plant growth remains excellent. Some traces of algae still remain, principly green spot algae.
Case Study #2

Initial conditions as of May, 1994: 160 L tank, 12 cm of 3 mm gravel with 1.7 kg of Terralit in the bottom 3 cm. Canister filter with carbon, 80W of cool white fluorescent light, CO2 fertilization, very small fish load (6 flame tetras). Water hardness approximately 120 ppm CaCO3 equivalent, pH ~7.0, temperature 25C, 25% change every few days.

Plant growth was slow, and brown algae that appeared to be a form of cyanobacteria (rapid growth in sheets, easy to remove) grew on the plants and substrate. Attempts to control the algae by frequent water changes and mechanical removal were ineffective. All water changes were accompanied by disturbance of the top 1 cm of the substrate.

Change: A potassium/iron fertilizer was added (0.9 ppm K, and 0.06 ppm FeIII) to the replacement water at water changes. The fish load was increased to 23 flame tetras (6 adult, 17 juvenile) and six otocinclus. The cool white lights were replaced with inexpensive plant tubes.

Effect: No change noted.

Change: K/Fe addition was stopped, and plant tablets (10-14-8) were inserted into the substrate in small pieces near plant roots. A total of 35g of tablets was added over a period of few weeks.

Effect: Some improvement in plant growth was observed. Unicellular green algae proliferated, reducing the visibility in the water to as low as 25cm. Frequent water changes had little effect on the algae.

Change: Fritz Super Clarifier (active ingredient(s) unknown) was added as directed to the tank water.

Effect: The unicellular algae became trapped by the filter. Because a recurrence was expected if the aquarium parameters were not altered, another change was made immediately:

Change: Addition of trace elements (homebrew formulation of Fe, Mn, Cu, Zn, B, Mo, and EDTA) with potassium sulphate at water changes. The dosage was computed to give 0.1ppm iron and about 1ppm potassium in the replacement water. Carbon was removed from the filter.

Effect: Plant growth improved, but blue-green cyanobacteria appeared and began to spread. Nitrates were found to be unmeasurable.

Change: Addition of potassium nitrate began in 1-2ppm NO3- doses, initially once every 5 days, increasing to daily once the author [Sears] became convinced of its lack of toxicity at these concentrations. Potassium sulphate, previously added to replacement water, was now dosed with the potassium nitrate at about 1-2ppm K. A commercial trace element mix (composition given in Appendix A) replaced the homebrew formulation. Magnesium sulphate addition was begun shortly after at a concentration of about 0.25ppm Mg.

Effect: Significantly better plant growth, but patches of cyanobacteria continued to grow on the plants and substrate. Green thread algae appeared on the brightly lit parts of plants. It was found that nitrate introduced to the water in 1-2 ppm doses was not detectable one or two days later.

Change: More plants were added. In the process, several old plants were uprooted, exposing the buried fertilizer tablets to the water.

Effect: Increase in green algae and blue-green cyanobacteria.

Change: Disturbance of the gravel at water changes stopped. Specifically, gravel vacuuming was discontinued, and replacement water was poured into the tank gently. Since the substrate evidently still contained considerable phosphate in the form of undissolved fertilizer tablets, it was thought best to disturb it as little as possible.

Effect: Algae of all types declined rapidly. It no longer appeared on the leaves of fast-growing plants, and apparently died and fell off the older leaves of slower-growing plants.

Change: Reduction of hardness of water to 60 ppm CaCO3 equivalent. This resulted in a drop of pH to approximately 6.7 (which was the reason for the change), and a temporary jump in the iron concentration in the tank, from less than 0.2 ppm to 2 ppm.

Effect: All Cryptocoryne sp. in the aquarium lost some leaves. Algae continued to decline.

Current status: All of the plants in the tank are growing well, including the Cryptocorynes that lost their leaves. Stem plants require weekly trimming, and floating plants need thinning every few days. The only algae in evidence are some small patches of cyanobacteria on the substrate and a little green algae on brightly lit parts of the Vallisneria gigantea, the Cryptocoryne balansae and the Bacopa caroliniana. Disturbance of the substrate (for replanting of cuttings) has led to minor algae outbreaks (green algae if the nitrate concentration is at least few ppm, cyanobacteria otherwise). Small amounts of (apparently dying) material are still in evidence on some of the oldest Anubias barteri var. nana leaves. The water change frequency has been reduced to 25% every two weeks.
Discussion

The observations in the case studies are consistent with the following hypothesis: when light, CO2, N, K, and all micronutrients and trace elements are present in slight excess relative to the amount of phosphate available for plant growth, certain higher plants in the aquaria are able to out-compete algae and cyanobacteria for the phosphate in the water column, starving them of this essential nutrient.

Exactly why higher plants should be able to outcompete algae for phosphate is unclear. Perhaps their roots give them some advantage, or they simply need much less phosphate than algae to thrive. Nor is it known which of the many plants in the test aquaria are responsible for stripping the water of phosphate, although the fast-growing duckweed and stem plants with roots growing above the substrate (notably Hygrophila spp.) are likely culprits. That phosphate is the factor limiting the plant and algae growth in the test aquaria has been reasonably well established; it is the only known plant nutrient not added to the 500L tank in any form other than fish food, and deliberately adding concentrated phosphate to this tank induced almost immediate algae growth (and a rapid duckweed explosion too). Since the plants continue to grow very well, they are clearly gaining preferential access to whatever phosphate is available. There may be some literature unknown to the authors that offers an explanation. If not, it should be fairly easy to conduct controlled experiments with a sensitive phosphate test kit and a few spare tanks containing only algae, one or two plant species, and nutrients. An experiment that shows that duckweed thrives at phosphate concentrations as low as X ppb, but green algae and cyanobacteria require significantly more than X, would offer strong support for the hypothesis.

According to the hypothesis, If the higher plants are unable to utilize all of the phosphate present in the water column because of a deficiency of some other nutrient, algae will thrive. The type of algae appears to depend on the availability of other nutrients. In the test aquaria, it was found that when nitrates were unmeasurable, cyanobacteria predominated. It is suspected that nitrogen deficiency favors the growth of cyanobacteria because these organisms can fix the atmospheric nitrogen dissolved in the aquarium water. When nitrates were available, green algae predominated. Some red algae was also observed in the 500L tank before CO2 fertilization was introduced. Because others have observed that tanks with CO2 fertilization have relatively little red algae [5], it tempting to speculate that at least some red algaes are able to utilize bicarbonate, giving them an advantage in aquaria where most of the available carbon is in this form (typically those with high carbonate hardness and high pH). The following paragraph summarizes the apparent relationship between nutrients, plants, and algaes:

If the aquarium is P limited, higher plants will outcompete algaes of all types for P, and the algae will disappear. If not, and N in the form of nitrates and ammonia is deficient, cyanobacteria will thrive, otherwise green or red algae will predominate. Red algae is favored over green algae if most of the available carbon is in the form of bicarbonates.

The factors that determine which species of algae will predominate in a given situation have obviously been greatly simplified. In [5], for example, nitrate concentrations in excess of 30ppm are claimed to be detrimental to the growth of green algae but not to cyanobacteria, so one would predict that cyanobacteria would predominate at high nitrate levels.

There is a tradition in the hobby of using fish food (usually processed by the fish first) as the source of all macronutrients for the plants in an aquarium. When this is done, it appears that first K and then N become the factors limiting plant growth (i.e. there is insufficient K and N in the food relative to the amount of P, at least for the fish foods the authors use). Thus, supplementary K and N must be added or free phosphate will be available to fuel algae growth (this contradicts the prevailing wisdom in the aquarium hobby that one of the ways to reduce algae growth is by reducing fertilization; in fact, additional nutrients are required). Other alternatives are to restrict feeding to the point where the growth of algae due to unused P is tolerable (another common piece of advice), an approach likely to result in poor plant growth due to nutrient starvation, or to use a phosphate-removing resin.

Some of the plant species in the 500L tank grow very slowly compared to the same species in the 160L tank (Echinodorus sp. in particular). The 160L tank has an enriched substrate with no deliberate water circulation, whereas the 500L tank has a relatively inert substrate with a 300gph UGF. It is highly unlikely that all plants are equally adept at extracting phosphates directly from the water column, and it appears that the fast-growing plants in the 500L tank are depriving the other plants of this nutrient which (thanks to the UGF) is distributed evenly throughout the tank. Slow-release phosphate tablets will be placed around the roots of these plants to see if growth improves. Both authors agree that the substrate design of the 160L tank (solid fertilizer at the bottom of an inert substrate) gives the better results, probably by making phosphate more-or-less equally available to all plants without allowing too much to leach into the water column where it is available to algae.

Conclusions

Despite the lack of controls on the various experiments, and the inability of the authors to directly measure phosphate in the aquaria, there is compelling evidence to support the hypothesis that all types of algae (including cyanobacteria) can be effectively controlled in planted aquaria by ensuring that phosphate is the factor limiting plant growth. In two aquariums with different volumes, substrates, lighting, and plant, algae, and fish populations, effective control of algae was achieved by enriching the tank water with CO2, micronutrients, trace elements, N, and K. Despite high initial algae loads, these tanks are now almost free of visible algae and have remained so for several months. Furthermore, in the 500L tank it was shown that phosphate limiting was occuring by adding phosphate to the tank water and observing the almost immediate growth of green spot algae and cyanobacteria. It has also been shown in the 160L tank that disturbances to the phosphate-containing substrate result in algal growth if there is significant (more than approximately 1 ppm) nitrate in the water, and in growth of cyanobacteria if nitrate is not present at this level. It is important to note that plant growth in both tanks is excellent, so algae control has not been achieved at the expense of the plants.

Recommendations

Plants cannot grow without phosphate. However, in order to keep a planted aquarium relatively algae free, free phosphate in the water column must be minimized. The following recommendations will help achieve this goal:

(a) A slight excess of light, CO2, K, N, micronutrients, and trace elements should be maintained to allow the plants to utilize all of the available phosphate. The authors recommend the following:

* 20-60 lumens/L illumination (about 2-4W fluorescent light per gallon), 12h/day
* 10-15ppm CO2
* 3-5ppm NO3
* 0.1ppm Fe
* 6.5-7.0 pH

Since inexpensive tests are not available for trace elements, micronutrients, or K, these items are dosed as some percentage of the measurable nutrients. The authors have had considerable success with mixtures that duplicate the relative concentrations present in Tropica Master Grow fertilizer [6]. For those readers wishing to “roll their own”, a balanced fertilizer recipe is given in the Appendix. Various commercial aquatic plant fertilizers are also available, but it may be necessary to purchase several products to ensure complete nutrient and trace element coverage. Daily dosing is highly recommended because it may prevent temporary nutrient depletion, which could make phosphate available on an intermittent basis and prevent the algae from starving.

As a general approach to optimizing plant growth and reducing algae, the following procedure is suggested:

1. Set the light and CO2 levels.
2. Add an iron-containing trace element mix (preferably one that already has Mg) to the tank every day, adjusting the quantity on a regular basis to achieve the target iron level. For mixes without Mg, add Epsom salts as well in the ratio of about 1.5-5.0ppm Mg to 1ppm Fe.
3. A week or so after reaching the target Fe level, check the nitrate level. If nitrates are below about 2ppm, proceed to the next step. Otherwise, add enough K2SO4 to the tank every day to drop the nitrate level to as close to zero as possible and keep it there (if the nitrates don’t drop, then something other than K is limiting plant growth and some detective work will be required to find it). Incidentally, measuring the nitrate level is helpful for general tweaking; if adding nutrient X causes the nitrate level to drop, then the tank is probably deficient in X.
4. Add enough KNO3 to the tank every day to get a 3-5ppm nitrate reading (one of the authors [Conlin] obtains satisfactory results with 10ppm).

Once the relative amounts of trace elements, K2SO4, and KNO3 have been determined, it becomes a simple matter (if desired) to concoct a liquid fertilizer that can be poured into the tank each day. Using a mix of dry powders is not recommended as powders tend to separate.

The procedure just described ensures that there will always be a slight excess of nitrogen in the tank. Some terrestrial plants will not flower if nitrogen is abundant, and this may be the case for some aquatic plants too. It would be an interesting experiment to withhold fertilization for several weeks after a lengthy period (say 6 months to a year) of good plant growth to attempt to induce flowering.

There is a possibility that some of the trace elements will accumulate over time to levels toxic to plants if regular water changes are not done. 25% water changes every second week should prevent this from happening.

(b) Grow fast-growing plant species that can efficiently extract nutrients directly from the water column. These plants will rapidly strip phosphate from the water, making it unavailable to algae. Floating plants (Lemna minor, Limnobium laevigatum) and stem plants that grow roots at internodes (Hygrophila sp.) are suggested for this purpose.

(c) Enriched substrates are probably the best means of supplying phosphates to plants provided steps are taken to minimize the leakage of phosphate into the water column. Substrate fertilizers such as Pond Tabs should be buried deep in the substrate where their nutrients are preferentially available to plant roots. Substrate circulation should be minimized to prevent phosphate from leaching too rapidly into the water column. Avoid gravel cleaning and other substrate disturbances if at all possible. Eliminating substrate circulation completely would not be desirable (even if it were possible) because supplementary fertilizers are usually added to the water and must be transported to the roots somehow.

(d) There will always be some residual algae in a planted tank because it is impossible to keep the water completely phosphate free. The amount of residual algae will be very small, but a good selection of algae-eating fish (Otocinclus sp., Farlowella sp., Ancistrus sp., Crossocheilus siamensis) and invertebrates (Caridina japonica shrimp and some snails) is desirable anyway for controlling the algae outbreaks that occur when the tank is first set up, the substrate is disturbed, or the nutrients are incorrectly dosed.

(f) Do not use phosphate buffers to control pH. Use of these buffers may produce phosphate concentrations as high as 100ppm, almost certainly resulting in very impressive algae blooms.

(g) Algicides such as simazine and copper are not recommended because they damage plants and may be unhealthy for fish as well [7][8].

(h) Miscellaneous considerations:

Tap water is not recommended as a source of trace elements because it may be deficient in one or more elements, and rapid plant growth is likely to deplete the elements far more quickly than they can be replaced.

Certain water treatment products (Aquasafe, NovAqua) should be avoided as they bind metals (including iron), making them unavailable to plants. They may also contain phosphate buffers. Simple dechlorinators or products such as Amquel are a better choice for treating tap water during water changes.

Carbon filtration may remove necessary trace elements from the water. With regular water changes and good plant growth, carbon filtration is not necessary and should be omitted.

(i) As a general principle, avoid adding fertilizers, water treatments, or any other products to one’s aquarium unless the products completely disclose the concentration of each ingredient present. Otherwise, there is no way to knowing what effect (if any!) these products will have on the aquarium’s inhabitants.

Acknowledgments

The authors would like to thank Ed Tomlinson for running various experiments on his tanks on our behalf. Various participants in the Aquatic Plants internet mailing list (too numerous to list here) have contributed many useful observations and insights. Finally, the efforts of the reviewers, Dave Huebert and Karen Randall, are greatly appreciated.

References

[1] Baensch, H. and Riehl, R. Aquarium Atlas, Tetra Press, 1987.

[2] Horst, K., and Kipper, H. The Optimum Aquarium, AD aquadocumenta Verlag GmbH, 1986.

[3] Booth, George “[F][plant] CARBON as a SUBSTRATE”, rec.aquaria newsgroup, 8 Aug. 1994 (also available on the Web).

[4] Frank, Neil “Nutrient Deficiency Symptoms”

[5] Baensch, H. and Riehl, R. Aquarium Atlas Volume 2, Tetra Press, 1993.

[6] Christensen, Claus “Re: Tropica Fertilizer”, Aquatic Plants Digest V1 #165, 5 July 1995.

[7] Frank, Neil “Chemicals to Control Algae – The Use of Simazine”, The Aquatic Gardener, Vol. 4 no. 6, 1991 (also available on the web).

[8] Gargas, Joe “Chemical Treatment of Ectoparasites Afflicting Fish Part I”, Freshwater and Marine Aquarium, Oct. 1993.
Appendix A – Fertilizer Recipe (Poor Man’s Dupla Drops)

* 1 Tbsp (~9g) Chelated Trace Element Mix (7% Fe, 1.3% B, 2% Mn, 0.06% Mo, 0.4% Zn, 0.1% Cu, EDTA, DTPA)
* 2 Tsp (~14g) K2SO4 (potassium sulfate)
* 1 Tsp (~6g) KNO3 (potassium nitrate)
* 2.5 Tbsp (~33g) MgSO4.7H2O (fully hydrated magnesium sulfate, aka epsom salts; omit if already present in trace element mix)
* 300mL distilled H2O
* 0.5mL 9M HCl (optional)

(Most of the ingredients can be purchased at hydroponics shops or garden supply stores. Epsom salts are available inexpensively at pharmacies)

Dissolve the trace element mix in 150mL distilled water, then add the remaining ingredients. Pour in additional water to make 300mL solution. The HCl helps prevent the growth of fungus and may be omitted if the mix is kept in the refrigerator. Add enough mix to the tank every day to keep the Fe level at about 0.1ppm (the exact amount will have to be determined by experimentation, but 3mL per 100L tank water is about right for a tank with rapidly growing plants). Measure nitrate levels regularly, and adjust the amount of KNO3 in the mix to maintain 3-5ppm (this step is fairly important). Those concerned about adding nitrates to their aquarium can dose the KNO3 separately, omitting it initially and adding it later as required to obtain the desired concentration.

The shelf life of the solution is unknown. Make small batches, or store only dry powders (but mix them with water before adding them to the aquarium).

If test kits are not available, satisfactory results can be obtained by adding 1mL mix to 10L replacement water during water changes.

Here are some comments from the Aquatic Plants Mailing List.
The original source for this document may be found c/o Ed Tomlinson

One of the biggest problems of trying to keeping Otocinclus catfish is during the first month of ownership. After that, if they are still alive they should remain so unless major mistakes are made by the fishkeeper. Otocinclus start out at the fish store in bad shape.

There are countless reports of fishkeepers losing Otocinclus in the first few weeks of obtaining them. It doesn’t seem to matter what type of tank the new fish are introduced to, they still drop like flies. Sometimes the entire group is lost, and at other times it’s only a few. What’s the deal?

Chemical Poisoning

Most hobbyists believe the trouble in keeping Otocinclus alive initially has to do with the whole capture/shipment process. Have you ever tried to net an Otocinclus among driftwood or heavily planted tanks? It’s nearly impossible! Now imagine trying to catch otocinclus with a large net in a body of water filled with plants, driftwood, and rocks. That’s exactly what the fish gatherers in South America are up against.

It is our belief that certain chemicals (Cyanide?) are added to the water either upstream or in a general area to slow down or temporarily paralyze these frisky little critters. The fish gatherers are then able to net them from the water in this weakened state. These chemicals could produce permanent damage to internal organs (such as the liver) and sometimes we will see hemorrhaging in the lower abdominal area in some stock.

Needless to say, I think it is wrong of the fish import industry to allow this to continue to happen, but we also are in an industry where certain fish are painted or injected with dye, or “soaked” to produce a more brightly colored fish. As long as people will purchase these fish, the industry will continue to produce them. Otocinclus are harvested in such large numbers that they remain one of the cheapest catfish (and therefore expendable according to importers) to buy. Only in serious hobbyist circles are tank-raised otocinclus considered to be much more valuable than their wild brethren. They were never poisoned so they live as long as most other tropical fish (5 years or more.)

Starving

Another reason why Otocinclus are in such bad shape in fish stores is that they are most often starving. As mentioned on the Feeding page, Otocinclus need to be constantly feeding in order to be healthy. The algae-free tanks within holding points at the exporter stations, not to mention the tanks at the store, are scraped clean on a regular basis which is not the right conditions for Otos to find some food to eat. Unless the Otocinclus are provided with vegetables (zucchini) or at the very least algae tablets at the fish store, they won’t last long in the tanks there.

What can we do?

So what can we do to help get these poor fish off to a good start in our tanks? Two main aspects we need to be attention to are clean water and lots of food.

Since Otocinclus are stressed (indeed what fish wouldn’t be?) from being kept in crowded fish store conditions, not to mention the ride home to your tank, it’s important to keep the water they are going to live in as clean as possible. This means NO Ammonia, NO Nitrites, and very low Nitrates (<20 ppm). This can really only be done with nice large water changes done frequently.

Keeping Otocinclus well fed is also important. In the beginning they’ll most likely be starving so it is important to introduce food immediately. This could be done by putting them in a tank filled with brown (diatom) algae. The excellent Little Monkeys article suggests this method. If you do not have a tank with brown or green algae then fresh vegetables should suffice.

Picking Healthy Otocinclus

It’s also important to pick healthy Otocinclus right from the get go. Due to the high mortality rate with otos it is a good idea to make sure the stock has been with the fish store for a couple weeks. Although it sounds harsh, this will “weed” out the weaker ones that don’t have a chance of survival anywhere.

A lot of otocinclus are in the store with worn fins, especially the caudal fin. Ideally the caudal fin should come to two sharp points on the edges, but in most cases they are rounded. This could be from stress or damage during shipment. In either case, most otos I’ve seen for sale have worn fins and unless it is severe don’t worry about it too much. They should grow out fine if your tank parameters are good.

Another good sign is if the otos in the store tank look well fed. Ask the store clerk what they are feeding the otocinclus… if they give you a blank stare or say “Flake food” then take your business elsewhere. When the fish have nice rounded bellies it usually means they are being fed. But not all rounded bellies are equal. If the otocinclus has a HUGE belly and looks as though it swallowed a marble it’s possible it may have a bacterial infection and not be overfed.

Conclusion

I hope this page doesn’t scare you away from purchasing these wonderful fish. They are really only fragile in the beginning. If your oto lasts for over a month, chances are that it will last a good long time if properly taken care of. They really are worth the effort in the beginning, and will provide much enjoyment for a long time thereafter.

www.otocinclus.com – Home of the Dwarf Suckermouth Catfishes

What is the Walstad Method?

This method of setting up an aquarium tank was made popular by Diana Walstad, author of the book ‘ECOLOGY of the PLANTED AQUARIUM – A Practical Manual and Scientific Treatise for the Home Aquarist’.

• Basically it’s a natural planted tank with a substrate containing a soil underlayer.

Alternative names

El Natural, NPT (Natural Planted Tank), Walstad Tank.

Principles

Provide an ecosystem where plants and fish balance each other’s needs. The soil underlayer insures that plants grow well enough to outcompete algae and recycle fish waste and toxins (e.g., ammonia, nitrite, etc). Without soil, plants don’t grow well enough to do “their
job”.

Aims

• Good plant growth
• No injected CO2 required
• No or little algae
• No need for plant fertilizers
• Supplies trace elements for fish health
• Stable environment for your pets
• No need to vacuum the substrate
• No need for frequent water changes– once the tank is established
• A smell-free tank.
• Biofilter may not be required (plants will take care of the ammonia, nitrite and nitrate, and the soil bacteria will also consume nitrogen).

Principle steps

• 1 inch layer of inexpensive, generic potting soil (or “top soil”) available from any garden centers or various home improvement stores. (John Innes number 3 recipe is ideal). Avoid soils containing chemical fertilizers (sulfates and nitrates will be converted to toxic H2S and nitrite after soil is submerged). Phosphate and calcium fertilizers (i.e., a little bone meal mixed with soil) may be beneficial. Get non-sterile ‘aquatic pond soil’ if it’s available.

• 1 inch of medium fine gravel (or very shallow layer of sand) to cover the soil layer (the soil bacteria need oxygen, so don’t smother the soil layer with rocks, driftwood, etc)

• If you have soft-water, you can mix in a calcium source (lime, coral gravel, shells, bone meal, etc) with the soil to make sure plants get enough calcium, GH for their initial set-up.

• For tank set-up, start out with many species of fast-growing plants (you want to find the ones that adapt best to your tank’s conditions). Examples: Hygrophila corymbosa, Shinnersia riv., Rotala rotundifolia, Ludwigia repens, Limnophila sessiliflora, Hornwort, Riccia, etc.

• Provide adequate lighting. This should be at least 2W per US Gallon (3.8L) of fluorescent lighting over the length of the tank for a period of at least 10 hours a day. ‘Cool white’ tubes are usually all that is required. If you can position the tank so that it can get a
  little sunlight for at least an hour a day, then do so (make sure water doesn’t overheat).

• Add room temperature conditioned (no chlorine or chloramine) water. Or add water conditioner right away.

• Provide enough water movement (via filters, power-heads, etc) to keep the water safely oxygenated for fish and soil bacteria. (Keeping water safely oxygenated is especially important the first two months with a freshly submerged soil). Water circulation near the water surface will break up possible bio-film development.

• Test water every two days for pH, ammonia, nitrite and nitrate (for at least two months or until you are sure they have gone). There may be a temporary increase in these levels while the soil is getting established (first 2 months), especially if the soil was artificially fertilized. Consider the use of Prime or Amquel daily to remove any potential total ammonia that may develop in the initial two months.

• If there are signs of algae, temporarily reduce lighting levels slightly or add floating plants. Main goal is to get plants growing well enough to out-compete algae.

• Do water changes as needed [some soils often require frequent water changes the first two months to remove miscellaneous toxins (e.g., wood oils) released by the soil. Also, new soils invariably release algae-stimulating nutrients (Nitrogen) the first couple
  months.] After tank is established, water changes can be very infrequent.

• You can add aquatic animals same day after set-up, but closely monitor fish health. It may be necessary (though unusual) during this “soil break-in period” to do some water changes to lower tannins. Some people use activated carbon in the filter if you wish to remove any yellow tannin effect (but realise these tannins are a health benefit to the tank animals).

• Monitor ammonia/nitrite levels for the first month. If you get any level above zero, act on them – perform a 25% water change! However if you add Prime or AmQuel+ daily for a month, you’ll protect the tank occupants against any possible harm from ammonia/nitrite and eliminate this chore.

Result

• Soil naturally contains nitrifying bacteria that will process and detoxify ammonia and nitrite. It also contains denitrifying bacteria that will process and remove nitrates.

• Plants will consume ammonia and nitrite, which they prefer to nitrates.

• The soil will release Carbonates (CO2) into the water that will greatly stimulate plant growth and stabilise KH. No Old Tank Syndrome.

• Fish waste (Mulm) and uneaten fish food will be quickly converted by soil bacteria into its component chemical parts so that plants can then use for their nutritional needs.

• Substrate with a soil under-layer should last many years (~10 years), because fish and plant waste will continuously replenish the nutrients that plants extract from the soil. No need to add fertilisers for years.

• The substrate releases trace elements that fish require for health therefore reduces need for water changes for this reason.

Fine-Tuning

• Trim the plants back as required and adjust the amount of light on the tank for fine tuning. More light, more plant growth, less algae.

• Consider adding small snails as these speed up the mulm breakdown.

• You’ll need a water hardness (GH) of greater than 7d. To raise GH you can add coral gravel or clean sea shells and let them slowly dissolve. However, adding a 4:1 mixture of calcium chloride and magnesium sulfate is one way to get the GH up immediately without increasing the pH.

• Ensure KH is never less than 6°d as you may get pH shifts at night which can harm your fish. See Sodium bicarbonate for details.

• Add slower growing plants like Hydrocotyle verticillata and Anubias once the fast-growing plants are established.

• Test your nitrate levels monthly (or sooner after adding fish) to ensure that nitrate levels are not rising too high (ie > 10 mg/l).

• Replace the lighting tubes every 9-12 months (compact fluorescent lights can go considerably longer).

Challenges

• Some people have difficulty uprooting and moving plants once water has been added to the tank. The main thing is to turn off the powerhead during this time so that soil particles are allowed to settle. The soil particles in a healthy, well-established aquarium
  should settle within an hour or two. [That's because soil bacteria have "glued" many soil particles together with their polysaccharide mucus.]

• Avoid disturbing the gravel during water changes, etc. One can place a dish or other flat object on the gravel to keep water additions from disturbing the soil layer.

• Fish load depends on plant growth, tank’s surface area, and water movement/aeration. Tanks with more fish provide plants with more nutrients and CO2. Conversely, tanks with robust plant growth can hold more fish. Often, the limiting factor is water oxygenation. For example, one can increase the fish load by simply increasing water movement and water oxygenation.

Soil types

Diana Walstad has recommended the garden soil ‘Scotts Lawn Care – Miracle Grow Organic Choice Potting Soil’ as sold in USA and UK.^[1]

• USA – Scotts Lawn Care – Hyponex Potting Soil.
• USA – Scotts Lawn Care – Miracle Grow Potting Soil.
• USA – Scotts Lawn Care – Miracle Grow Organic Choice Potting Soil.
• UK – Miracle-Gro – Organic Choice All Purpose Peat Free Compost.
• UK – Miracle-Gro – Organic Choice Premium Garden Soil
• UK – J. Arthur Bower’s – John Innes No.3 Soil-based compost
• UK – J. Arthur Bower’s – Aquatic Compost.
• UK – Scotts Levington – John Innes No.3 Compost

• ‘Scotts Lawn Care Miracle Grow’ is known as ‘Scotts Miracle-Gro’ in the UK.

• Tip – look for soil marked as having a pH of ~6.0-7.0 if possible. Test the soil pH or ask the manufacturer if necessary. Avoid heavy manure-based soils. Avoid ‘Ericaceous Compost’ as it may be too acidic. Try not to use soil with peat in it as it may be too acidic.
  Try not to use soil with wood shaving as it may cause more organic breakdown and lots of tannins being released.

• The name ‘John Innes’ is actually a recipe for soil. See John Innes Manufacturers’ Association for more info.

Who is Diana Walstad?

Diana lives in North Carolina, USA and is technical advisor for the AGA (Aquatic Gardeners Association).

References

1. ↑ Diana Walstad soil recommendation on Aquatic Plant Central – El Natural forum

Links

• See also MS – Mineralised soil.

Articles

• How to: Pot Aquarium Plants in Topsoil by Betty Harris

Book

• Diana’s book – Amazon UK
• Diana’s book – Amazon USA
• Diana’s book – Amazon GER
• Electronic version of book available from – Atlas Books

Forums

• Diana Walstad Gallery
• PLANTS and BIOLOGICAL FILTRATION by Diana Walstad
• building el-natural 6 gallon tank
• What is “el-natural”? Step-by-step
• Setting up a Walstad Natural Planted Tank. By Betty Harris
• Some issues with soil in a NPT
• Setting up a Walstad-Type Natural Planted Tank by Betty Harris

• Diana’s El Natural forum

HETERANTHERA ZOSTERIFOLIA

Hardiness: Easy
Light Needs: Medium
Plant Structure: Stem
Family: Pontederiaceae
Genus: Heteranthera
Region: Central/South America
Location: Brazil
Size: Individual stem width: 5-12cm (2-5in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Heteranthera zosterifolia, often called stargrass, is a native of Brazil where it grows in still water and in marshy areas. This fragile, soft-leaved plant is now relatively common in the aquatic plant hobby.

H. zosterifolia is relatively easy to grow and an excellent indicator of aquarium conditions. Although it can be grown in lower light (down to 1.75 watts per gallon with power compact bulbs) and non-CO2 conditions, it really does show its full potential under high light and pressurized CO2 injection with leaf size becoming larger and internode length shortening. Small, stunted growth under high light is usually the result of too lean nutrient conditions, as this is a very macronutrient hungry plant (NO3 of 10 ppm or more and PO4 of 1 ppm or more for exceptionally large, lush growth). It reacts to a sudden lack of nitrate by turning transparent and melting away. Phosphate deficiencies result in very dark green, compact plants. Iron and micronutrient deficiencies result in white creases or black edging on the leaves.

H. zosterifolia is a very maleable plant, responding well to pruning the tops off and leaving the rooted portions. With this treatment, stargrass produces a profusion of new side shoots which results in very dense, bushy growth. If allowed to grow along the surface, the plant often produces beautiful blue flowers.

This plant is popularly used in both Dutch and Nature Aquarium style layouts and for good reason. It is often pruned short as a foreground plant, allowed to grow tall as a background plant, or pruned as a midground hedge or street. It is a highly recommended, aesthetically pleasing plant for the aquascape.

HYDROCOTYLE VERTICILLATA

Hardiness: Moderate
Light Needs: High
Plant Structure: Rhizome
Family: Apiaceae
Genus: Hydrocotyle
Region: Americas
Location: North and South America
Size: 3-7 cm (1-3in)
Growth Rate: Medium
Can Be Grown Emersed: Yes

Hydrocotyle verticillata is a common weed found throughout the warmer regions of the Americas, growing in areas ranging from poorly-drained soils to shallow water. It differs from the more commonly available H. leucocephala in that the leaves are entire (like a miniature parasol) and not incised (cut) at the base. There seem to be many H. verticillata look-a-likes in the trade that grow significantly taller. The true H. verticillata is uncommon in the U.S. trade, although both Tropica and Oriental Aquariums grow it.

H. verticillata is not too difficult to maintain in the aquarium. The most important factor is lighting, as the height of this plant will be determined by lighting intensity. The stronger the lighting, the shorter this plant will be. Otherwise, this plant is not too fussy about CO2 or fertilization, although a well balanced nutrient regime and CO2 injection do greatly enhance growth and overall health.

This interesting little plant, unlike H. leucocephala, retains its trailing growth habit when submersed. When first planting, cut the runners into segments that include one leaf. Plant the runners horizontally into the substrate. Soon, this Hydrocotyle will begin to put out new runners. Control it by cutting unwanted runner segments with a sharp pair of scissors.

Because of its unique, umbrella-like leaves and short height, H. verticillata makes a charming foreground accent plant where the leaves look like miniature, green toadstools or mushrooms. In larger aquariums, it can be used as the main foreground plant in place of more typical species like Glossostigma elatinoides, Eleocharis spp., and Riccia fluitans.

ROTALA ROTUNDIFOLIA

Synonyms: Rotala indica (erroneous)
Hardiness: Easy
Light Needs: Medium
Plant Structure: Stem
Family: Lythraceae
Genus: Rotala
Region: Asia
Location: Southeast Asia
Size: Individual stem width: 1.5-2cm (0.75-1in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Rotala rotundifolia is a classic aquarium plant. While its origins are in southeast Asia, where it grows as a weed in rice paddies and wet soils, it now can be found through many parts of the United States. In the U.S., it was introduced with rice seeds shipped to the southeastern United States. This plant can be differentiated from the closely related R. indica by the differences in the two species’ inflorescences. R. rotundifolia bears groups of terminal inflorescence while R. indica has solitary flowers on the axis of the leaves. R. rotundifolia is now one of the most commonly available aquarium plants available through online venders as well as many local fish stores, although it is still frequently sold in error as R. indica .

R. rotundifolia is an easy red plant to grow in the aquarium. While it will grow in medium light, this plant really needs high light to show its true colors. When lit well, the plant will grow at an angle over the substrate instead of straight up. To encourage red coloration, R. rotundifolia should be kept well lit (2.5 watts per gallon or more) with no shading. Lean nitrate levels (~5 ppm), high phosphate levels (~1.5-2 ppm), and heavy iron/micronutrients dosing will help produce intense colors out of this plant. By varying these conditions, one is able to bring out various shades from pink to yellow.

To propagate, simply snip off a healthy stem and replant into the substrate. Pruning off the top portions of this plant and leaving the rooted portions in the substrate promotes very bushy growth as the plant should produce a multitude of side shoots. Pruning can also be done by discarding the rooted portions and planting the top portions into the substrate. If allowed to grow on the surface, the plant will also produce many side shoots from each node along the stem.

In aquascaping, this versatile plant can be used in the midground and background positions as a focal point or reddish accent. It is commonly used in both Nature Aquarium style and Dutch style layouts.

LUDWIGIA REPENS

Hardiness: Easy
Light Needs: Medium
Plant Structure: Stem
Family: Onagraceae
Genus: Ludwigia
Region: North America
Location: Southern North America
Size: Individual stem width: 5-8 cm(2-3in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Ludwigia repens, a classic aquarium plant, grows along the margins of any freshwater body of water (ditches, rivers, lakes, ponds) in the southern United States, Central America, and the Caribbean Islands. In the wild, it is a very polymorphic species in that it readily crosses with other species of its genus. This characteristic makes identification between geographical varieties difficult. L. repens is now one of the most commonly available aquarium plants around the world.

L. repens is one of the easiest red plants to grow in the aquarium, being able to grow in even lower light conditions (down to 1.75 watts per gallon with power compacts). It also makes an excellent candidate for moderately lit, non-CO2 aquaria. When lit well, the plant will grow at an angle over the substrate instead of straight up. To encourage red coloration, L. repens should be kept well lit (2.5 watts per gallon or more) with no shading. Lean nitrate levels (~5 ppm), high phosphate levels (~1.5-2 ppm), and heavy iron/micronutrients dosing will help produce intense colors out of this plant. Some hobbyists have noted that 9325K plant bulbs will also enhance red coloration.

To propagate, simply snip off a healthy stem and replant into the substrate. Pruning off the top portions of this plant and leaving the rooted portions in the substrate promotes very bushy growth as the plant should produce a multitude of side shoots. Pruning can also be done by discarding the rooted portions and planting the top portions into the substrate. If allowed to grow on the surface, the plant will also produce many side shoots from each node along the stem.

In aquascaping, this versatile plant can be used in the midground and background positions as a focal point or reddish accent. With intense pruning, the plant can even be used as a foreground plant in large aquaria.

BLYXA JAPONICA

Hardiness: Moderate
Light Needs: Medium
Plant Structure: Stem
Family: Hydrocharitaceae
Genus: Blyxa
Region: Asia
Location: Tropical Asia
Size: Height: 7-15cm (3-6in)
Growth Rate: Medium
Can Be Grown Emersed: No

CRYPTOCORYNE WENDTII ‘GREEN GECKO’

Hardiness: Very Easy
Light Needs: Low
Plant Structure: Rosette
Family: Araceae
Genus: Cryptocoryne
Region: Cultivar
Location: Cultivar
Size: Height: 10-15cm (4-6 in)
Growth Rate: Slow
Can Be Grown Emersed: Yes

Cryptocoryne wendtii ”green” is suitable for small aquariums. When grown in an open space the leaves will virtually lie on the bottom. Like most other Sri Lanka Cryptocorynes, it also grows well in hard water. Like many other plants, it can be affected by cryptocoryne disease. One way to prevent this is by only leaving the 4-5 newest leaves on the plant when planting. It is a good foreground plant, even in small aquariums.

MICROSORUM PTEROPUS ‘WINDELOV’

Hardiness: Very Easy
Light Needs: Low
Plant Structure: Moss / Fern
Family: Polypodiaceae
Genus: Microsorum
Region: Cultivar
Location: Cultivar
Size: Height: 10-20 cm (4-8 in)
Growth Rate: Slow
Can Be Grown Emersed: Yes

Microsorum pteropus ‘Windeløv’ is a patented variety of Microsorum pteropus, named after Tropica’s founder Holger Windeløv. Its finely branched leaf tips make it one of the most beautiful aquarium plants. A hardy and easy plant for both beginners and the more experienced. Best results are obtained by planting it on a stone or tree root. If planted in the bottom the horizontal rhizome must not be covered. This plant is not eaten by herbivorous fish.

SAGITTARIA SUBULATA

Hardiness: Easy
Light Needs: Medium
Plant Structure: Rosette
Family: Alismataceae
Genus: Sagittaria
Region: North America
Location: Eastern United States
Size: Height: 5-15cm (4-6in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Sagittaria subulata, a marsh plant, is found in the Eastern U.S. and South America in both fresh water and brackish locations. S. subulata is a well-known, popular aquarium plant which is currently cultivated by most major nurseries including Oriental Aquariums, Tropica, and Florida Aquatic Nurseries. Sagittaria subulata is readily available in well-stocked stores listed usually as ‘Dwarf Sagittaria’.

S. subulata is a fairly easy plant to grow, requiring only moderate light. This plant species can tolerate quite hard, alkaline water conditions. Also, this plant species does well in non-CO2 aquaria, although CO2 injection does greatly enhance growth. Either a rich substrate or rich water column with ample amounts of phosphate, nitrate, potassium, and iron/micronutrients will produce the best results. This plant is especially finicky about iron levels and will show deficiencies with yellowing leaves. Intense lighting will bring out reddish leaf apexes.

Planted densely, the 0.5cm wide leaves have the ability to grow to 60cm. Less dense plantings keeps the leaves short, in the 5-10cm range. S. subulata is a fast grower, and as it propagates by runners, it can quickly form a dense carpet. Sometimes, this plant will send long flower stems to the surface which bear small white flowers.

The relatively short height of this plant makes S. subulata ideal for foreground or midground locations or in dense plantings. This grassy textured plant can also be accented with other plant species such as Anubias barteri var. nana and Glossostigma elatinoides for contrast and a more natural appearance. If allowed to grow up to 60cm, then it can be used in the background to create vertical strokes in a layout.

EGERIA DENSA

Hardiness: Very Easy
Light Needs: Medium
Plant Structure: Stem
Family: Hydrocharitaceae
Genus: Egeria
Region: Central/South America
Location: Brazil, Argentina, Uruguay; introduced to other continents
Size: Individual stem width: 3-7 cm (1-2.5 in)
Growth Rate: Very fast
Can Be Grown Emersed: No

Egeria densa, as probably one of the most popular aquarium and pond plants of all time, has also been known as Anachris, Brazilian Elodea, and sometimes as simply Elodea, a name stemming from its previous classification in the genus. Though this species has been introduced into bodies of water on every continent except for Antarctica, its natural distribution is comprised of only parts of Brazil, Uruguay and Argentina. It can be found growing in deep, stagnant or slow-moving bodies of water, and it is readily available in quantity far and wide.

E. densa is among the most easily grown aquatic plants offered for sale today. It will grow either floating or anchored in the substrate at a rate which, if it finds the ambient conditions to be agreeable, is emphatically rapid. This fact lends to its use as an efficient oxygenating agent in both ponds and aquaria. Though hard, lime-rich water and lower temperatures are favored most, this species can endure higher temperatures for a short period of time and growth is only marginally slowed by softer water. CO2 will unquestionably boost the growth rate of this species even though otherwise it could still be described as epidemic. In ponds during the summer, this species will often develop its characteristic white, three-petal flowers. It should also be noted that this species is an effective user of bicarbonate.

Propagation of E. densa is straightforward and trouble-free. All the aquarist needs to do if he or she desires more plants is to sever the top section a the stem and replant it. The bottom portion of the severed stem will soon develop lateral shoots. In floating plants, lateral shoots are far more common and can be cut from the main stem. They will soon spread.

The use of this plant in the aquascape is admittedly limited due to its rapid growth and aversion toward higher temperatures. Nonetheless, if the aquarist is shrewd in his or her pruning practices, an effective backdrop can be rendered with this species. With its deep green color and semi-translucent leaves (they are only two cell layers thick), this species can lend a distinctive texture to the home aquarium.

Young plants initially start with a seedling stem with roots growing in mud at the bottom of the water; further adventitious roots are produced at intervals along the stem, which may hang free in the water or anchor into the bottom. It grows indefinitely at the stem tips, and single specimens may reach lengths of 3 m or more.

The leaves are bright green, translucent, oblong, 6-17 mm long and 1-4 mm broad, borne in whorls of three (rarely two or four) round the stem. It lives entirely underwater, the only exception being the small white or pale purple flowers which float at the surface and are attached to the plant by delicate stalks.

It is dioecious, with male and female flowers on different plants. The flowers have three small white petals; male flowers have 4.5-5 mm petals and nine stamens, female flowers have 2-3 mm petals and three fused carpels. The fruit is an ovoid capsule, about 6 mm long containing several seeds that ripen underwater. The seeds are 4-5 mm long, fusiform, glabrous (round), and narrowly cylindrical. It flowers from May to October.

It grows rapidly in favorable conditions and can choke shallow ponds, canals, and the margins of some slow-flowing rivers. It requires summer water temperatures of 10-25 °C and moderate to bright lighting.

It is closely related to Elodea nuttallii, which generally has narrower leaves under 2 mm broad. It is usually fairly easy to distinguish from its relatives, like the Brazilian Egeria densa and Hydrilla verticillata. These all have leaves in whorls around the stem; however, Elodea usually has three leaves per whorl, whereas Egeria and Hydrilla usually have four or more leaves per whorl. Egeria densa is also a larger, bushier plant with longer leaves.

GLOSSOSTIGMA ELATINOIDES

Hardiness: Moderate
Light Needs: High
Plant Structure: Stem
Family: Phrymaceae
Genus: Glossostigma
Region: Australasia
Location: Australia
Size: 2-3 cm (1-1.5in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Glossostigma elatinoides, one of the smaller aquarium plants, is a prostrate herb that can be found growing in swamps and inundated areas in Australia. It can be distinguished from the closely related G. diandrum in that it has four stamens within the flower instead of two. In the 1980s, Takashi Amano discovered this (then) uncommon, unpopular plant while reading an issue of European Aquarium Style Magazine. He imported the plant into Japan through the nursery Dennerle. With these imported specimens, he created the first Nature Aquariums with low-growing carpets of Glossostigma. Now, G. elatinoides is one of the most popular foreground plants in the world.

This small aquarium plant is fairly easy to grow in aquariums with decent lighting and CO2 injection. When lit well (at least 2 watts per gallon with power compact lighting, preferably more) and planted well (see below), this plant will respond by quickly carpeting an aquarium with prostrate runners. When poorly lit, G. elatinoides will respond by growing upright. For fastest growth and vigor, this plant prefers regular additions of nitrate (5 ppm or more), phosphate (0.5 ppm or more), and iron into the water column. This plant will respond to low nitrate by yellowing and prematurely losing its older leaves. Phosphate limited situations will result in slow growth and a dark green color. When it is not getting enough iron and traces, transparent patches will appear on the leaves.

When one first receives it, Glossostigma is usually in its emersed form. Plant the stems in groups of three to four and allow two weeks for new submersed growth. Pull out the bunches and snip off the submersed growth with a pair of scissors. Take a stem with a pair of tweezers and run it horizontally under the substrate until it is completely buried. Clear away some substrate until a couple green leaves are visible. The plant should begin to grow horizontally and cover the foreground in a matter of weeks if well lit, provided with ample CO2, and nutrients.

G. elatinoides is usually planted in the foreground where it forms a low growing, dense carpet typically in Nature Aquarium/Amano style layouts. This plant can also be used as a foreground accent. Individual runners form excellent larger leaved accents when growing along a Riccia foreground.

HYGROPHILA POLYSPERMA

Hardiness: Very Easy
Light Needs: Low
Plant Structure: Stem
Family: Acanthaceae
Genus: Hygrophila
Region: Asia
Location: India, Bhutan
Size: Individual stem width: 8-15cm (3-6in)
Growth Rate: Very fast
Can Be Grown Emersed: Yes

The stout Hygrophila polysperma is by and large a universal aquarium plant that is easily acquired. It has been a part of the aquarium plant hobby for many years due to its uncomplicated nature. This tough plant can be found growing predominantly in India and Bhutan.

Few aquatic plant species are as tough or as accommodating as this one. Light intensity seems to be rather unimportant, though lower light values will result in proportionately slower and more diminutive growth. Fertilization, as well, seems to be of limited significance in the maintenance of this species. Its stems will tolerate a variety of hardness values without showing a noteworthy decline in their exceptionally quick growth. CO2 supplementation is definitely not a necessity for this species, and it can be grown in non-CO2 aquaria without problems. In this light, it is a recommendable beginner’s plant.

Since H. polysperma develops a multitude of lateral shoots at its leaf nodes, propagation is a simple matter of removing these and replanting them. An aquarist might also “top” the stems by removing and discarding all of the shoot apexes that rise above a given level in the aquarium; new growth will shortly materialize. The growth of this species is often so rapid that a trim of some sort is required within two or three weeks of the last pruning.

A group of stems of H. polysperma is best suited to the midground area of the aquarium, where they will add an interesting geometry to the aquascape. They are of limited contrast value, making them excellent ‘filler’ plants in stem plant dominated layouts. Although most hobbyists discount the decorative value of this species, Takashi Amano frequently uses this plant in his layouts.

CRYPTOCORYNE PONTEDERIIFOLIA

Hardiness: Easy
Light Needs: Low
Plant Structure: Rosette
Family: Araceae
Genus: Cryptocoryne
Region: Asia
Location: Sumatra
Size: Height: 5-12
Growth Rate: Slow
Can Be Grown Emersed: Yes

Cryptocoryne pontederiifolia is a marsh plant found only on the western coast of Sumatra, one of the largest islands in the Indonesian Archipelago. This plant is also naturalized in Singapore, where it can be found in marshy soils along forest streams. It can be differentiated from the similar C. moehlmannii by the sulfur yellow inflorescence. Although still uncommon in the United States, C. pontederiifolia has long been popularly cultivated by hobbyists in Europe.

This robust Cryptocoryne sp. is unproblematic and adaptable in aquarium culture. Water conditions can range from soft to hard and from weakly acid to neutral. CO2 injection and intense lighting will cause the plant to become bushier and more compact while moderate to dim lighting will result in leggier, taller ones.

When first introduced into an aquarium, this plant will require several weeks of adaptation before growing commences. Afterward, growth is moderate to rapid. Unlike most Cryptocorynes, this species rarely suffers from ‘melting.’ Propagation can be done by splitting the daughter plants, formed by runners, from the mother plants.

The broad, textured leaves of C. pontederiifolia make it an excellent choice for the midground to background of medium to large aquariums where they can be used as an alternative to Anubias spp. It is occasionally used to form Dutch streets in large aquaria in Europe. It is also very attractive in the midground of Nature Aquarium style aquascapes among dark mosses and grassy plants. In medium size aquariums, this plant can also be used as a specimen plant.

LUDWIGIA PALUSTRIS

Hardiness: Easy
Light Needs: Medium
Plant Structure: Stem
Family: Onagraceae
Genus: Ludwigia
Region: Cosmopolitan
Location: Americas, North Africa, Europe, Asia
Size: Stem width: 4-7cm (1.5-3in)
Growth Rate: Fast
Can Be Grown Emersed: Yes

Ludwigia palustris, as its name implies, can be found chiefly in palustrine (swampy) environments across the globe (excluding Australasia). This extremely variable species can be found growing creeping and submersed in shallow pools and other types of stagnant and/or slow-moving waters. It has been regularly available for many years, sometimes as ‘Red Ludwigia’ and sometimes erroneously as L. mullertii (a name under which the venerable L. repens has also been cultivated). However, in recent years, it has become increasingly common (and is now the rule more so than the exception) for plants offered for sale as ‘Red Ludwigia’ to be the cultivar L. palustris x L. repens instead of pure L. palustris. This is also the case, unfortunately, for many of the plants actually offered for sale as the genuine L. palustris. A variety of this species that always remains green is sold by the German plant nursery Dennerle.

The main element required to encourage the satisfactory growth of L. palustris in the aquarium is sufficient light. Although medium values are tolerated, only high light will prevent the plant from becoming leggy and greenish. Macronutrient fertilizers, particularly nitrate and phosphate, are much appreciated by this species despite the fact that it will grow without them. Micronutrient and CO2 fertilization are also not required, but their inclusion will enhance both color and growth. Also, unlike many plants native to temperate areas, L. palustris is quite adaptable to varying temperatures and has no difficulty growing in warmer water. Under high light values, the stems of this species tend to grow at an angle, especially if the substrate is rich. Many roots and lateral shoots will form on the nodes of this plant. In cultivation outdoors in ponds or tubs, L. palustris will produce flowers with four green sepals (no petals) and four yellow stamens. The flower of this species is frequently the characteristic that most easily sets it apart from other species in the Ludwigia genus, though even this can sometimes be problematic because it is possible for L. palustris x L. repens to produce the same flower. Despite this fact, L. palustris can sometimes be differentiated from L. repens and L. palustris x L. repens on the basis of its comparatively longer petioles (the thin section connecting the leaf to the stem). Also, plants with reddish leaf edges, stems, and/or central veins are usually L. palustris, though some varieties of L. repens have been shown to possess similar characteristics.

The topping method of pruning a stem and replanting the severed portion is a good way to propagate this species, since a multitude of new shoots will soon develop on the nodes of the section left in the substrate.

Although the use of this species in the aquascape greatly depends on what color form is being cultivated by the aquarist, the reddish form (which is by far the most common) is the most decorative. That said, the shoots of this species form an excellent eye-catching focus if planted in a graduated or tiered group in the middle zone of the aquarium, where they will contrast best with light and dark green species with fine leaves.

ELEOCHARIS PARVULA

A low-growing Eleocharis that forms runners close to the parent plant. It is prettiest planted in small bunches quite close to each other, which will gradually form a solid mass of plants. An ideal foreground plant, equally suited to large and small aquariums. Its scientific name is at present uncertain.

HEMIANTHUS CALLITRICHOIDES “CUBA”

Hardiness: Moderate
Light Needs: High
Plant Structure: Stem
Family: Scrophulariaceae
Genus: Hemianthus
Region: Central/South America
Location: Greater Antilles (Cuba, Hispaniola, Jamaica, Puerto Rico), Bahamas
Size: Individual stem width: 0.5cm (0.25in)
Growth Rate: Medium
Can Be Grown Emersed: Yes

Hemianthus callitrichoides, sometimes known as ‘dwarf baby tears’, or more commonly as ‘HC’, was discovered by Tropica founder Holger Windeløv during an expedition to a small rocky steam east of Havana, Cuba; it was described in aquaristic literature for the first time in 2003. Since its introduction into the hobby, H. callitrichoides has become increasingly popular and a foreground plant of choice, making this once rare plant moderately easy to obtain.

H. callitrichoides is generally moderate to slow growing in the aquarium. It requires abundant lighting, generous nutrient levels, a fine-grained substrate and good CO2 levels to do well in the aquarium and will respond with a great deal of pearling if those things are provided. Two watts or more per gallon of compact fluorescent lighting or an equivalent light source will keep it growing close to the substrate. A good rule of thumb for this plant is this: The more light and CO2 available, the more the plant will thrive. Flourish Excel is accepted well by this plant and its use will result in noticeable growth improvements. H. callitrichoides can be grown emersed but is somewhat prone to fungal attack if the soil is not thoroughly saturated with water. A rich substrate like Aquasoil and intense lighting are recommended. The plant will flower with tiny white blooms if grown emersed, but the flowers are extremely small and easy to overlook.

In an aquascape, H. callitrichoides is sometimes planted between rocks or over wood to give an aged look. More frequently, it is used as a general foreground cover, often in combination with other foreground plants such as Eleocharis species. Its small size makes it especially useful for nano aquariums. When planting H. callitrichoides, there are two main techniques. The first is to plant small half inch plugs in the substrate at roughly one inch intervals. The second is to carefully plant individual stems close together with a good pair of tweezers (rooting fish will cause stems to be dislodged). There is some debate about which method is best for the fastest coverage, but both work well given good growing conditions.

POGOSTEMON HELFERI

Hardiness: Moderate
Light Needs: Medium
Plant Structure: Stem
Family: Lamiaceae
Genus: Pogostemon
Region: Asia
Location: Thailand
Size: Stem width: 2-5cm (1-2 in)
Growth Rate: Medium
Can Be Grown Emersed: Yes

Traditionally, when setting up a new tank, the tank must be “cycled”. Cycling is the process of allowing the nitrifying bacteria to build up in the tank, and in the filter. These bacteria convert the harmful ammonia and nitrite into nitrates. This cycling takes approximately 6 weeks. The amount of bacteria that grow is determined by how much ammonia and nitrite are being produced by the fish.

Consider this: The Bio-filter bacteria convert ammonia and nitrites into nitrates. Plants can use all three of those as their source for nitrogen. In fact, ammonia is the preferred nitrogen source for plants. If you add plants to a tank with an established bio-filter, the plants will actually use up some of the ammonia before the bacteria can convert it. That means that there will be less ammonia for the bacteria, so the bacteria colony will decrease in size. And since less ammonia is now being converted to nitrite, there will be less nitrite than before, so some of those bacteria will die off too.

So, a logical question would be: Why go thru the trouble to build up a large bio-filter bacteria colony, when it will just shrink when you later add plants? And the logical answer is: Don’t!

I recommend starting out with the plants doing the job of removing harmful ammonia. In order for this to work, you must ensure that the plants are growing and thriving before adding the fish.

My plan for setting up a new planted tank involves setting up all the tank equipment, including CO2 and Lighting, then adding plants, and giving them several weeks to get established before adding any fish. During those several weeks, the plants will get their roots established, use up any nutrients already present in the water (and begin using substrate fertlizers provided), but the algae will starve, since you aren’t adding any fish food, and there is no fish waste for those couple weeks. This lets the plants get a head-start on the algae, and ensures a beautiful algae-free tank.

So, the detailed plan:

1. Set up tank equipment including filtration, CO2, lighting, substrate, heaters, light-timers.
2. fill tank with water, dechlorinate, and let equipment run for a day or two, just to be sure you aren’t going to need to tear it down.
3. Add plants. Lots of them. Mostly fast growing plants to start with. Watch out for crypts and apons, which might melt due to changing water conditions. Don’t add any water column fertilizers. Substrate fertilizers are ok.Recommended fast growing plants include: Stem plants like Ambulia, Hygro, Wisteria, hornwort, Water Sprite. Floating plants like Duckweed and Frogbit, and large amazon swordplants. Surprisingly, Java Fern can also be an excellent fast-grower when supplied with high CO2 and high light levels. I recommend planting with lots of the basic stem plants. Once things get established, you can remove some of the boring stem plants, and replace them with more exotic plants. You will almost certainly need to re-do your landscaping anyway, as you will surely find some plants which started out small are now too big, and they need to be moved to a position in the tank where they won’t hide the smaller plants.
4. For the next two weeks, don’t add any anything except maybe more plants. Just monitor CO2 levels, get the CO2 setting stable for when the fishies are added.During this stage, I like to “over-dose” my CO2 levels. While recommended CO2 levels in a tank containing fish would be around 15-20ppm, since there are no fish in the new tank yet, you can safely push the CO2 level higher, which can boost plant growth to amazing levels. I did about 30ppm during this stage. If you do this, be sure to decrease the CO2 level and let the CO2 stabilize at the 15-20 ppm level before adding any fish.
5. Begin adding fish. Algea eaters should be the first ones into the tank. I added 5 otos, and 2 SAEs as the first fish in my 75g. I also added some snails (MTS and red ramshorns). Again, no fish food. Let the algae eaters live off of any minor algae that appeared during the first two weeks.NOTE: SAEs and Otos aren’t recommended for cycling. But in the case of a heavily planted tank, these fish won’t be exposed to cycling conditions. With good light, CO2 injection, and fast growing plants, there will never be a measurable ammonia or nitrite spike.
6. Each week, add some more fish until you reach your desired stocking level. Once you start adding non-algae eaters, start feeding. Yes, the algae eaters will eat some food, but they will still eat algae. Don’t add too many fish in any one week, or you might generate more ammonia/nitrite than your bio-filter and/or plants can handle. I added 5 more otos, and 3 more SAEs in my second “stocking” week. Then I added 5 cories and a pair of rainbows by third, etc. Not too many, but enough that you don’t go crazy staring at a mostly empty tank.
7. After the tank has been up and running for about 8 weeks, you can start thinking about adding fertilizers to the water. Measure your nitrate level, to determine if KNO3 should be added. See my other article, “Adding Nitrate to a planted tank” if your nitrate levels are below 5ppm.Also figure out if you should add a trace mix. You can figure this out 2 ways: With a test kit, or by observing plants. Iron deficiency shows up quickly in some plants. New leaves will be yellow or pale. My favorite iron indicator plant is Frogbit. It will show an iron deficiency within a day or so, and leaves will regain their green color in just a couple days once iron levels are good. Most trace mixes are prepared so that by adding enough to get iron levels right, the rest of the elements are right too. My favorite trace mix is TMG (Tropica MasterGrow). Here in the US, there are a couple sources for TMG. One is from Dave Gomberg’s JCF Systems. The price on the bulk 5 liter size is a very good deal. For smaller quantities, I like ordering it from Big Al’s Online. A 500ml size is $10.99. A very good deal, and I’ve had good experiences with Big Al’s.

By the end of this process, your tank will contain some amount of the normal bio-filter bacteria. These bacteria will be able to handle any excess ammonia produced by your fish. Those bacteria will establish themselves just as they do in a non-planted tank. In fact, the plant surfaces will often carry some of those bio-filter bacteria into the new tank.

I’ve used the above method to start 4 new planted tanks (only one of which was my own). It’s worked exactly the same each time, and all four are now beautiful algae-free planted tanks.

As always, the standard disclaimers apply: Your mileage may vary. Past performance does not guarantee future results.

Be sure to test your water. Test for ammonia and nitrite at least once a week during this process. I’ve never had a problem, but I don’t want your fish dying just because I’ve gotten lucky in the past. If you see signs of stress in your tank, check the ammonia/nitrite/pH levels right away. If something in your tank is hindering plant growth, then the plants won’t be able to use up the ammonia/nitrite, and levels could get dangerous until the bio-filter bacteria get established.

I strongly recommend against using this method if you don’t have medium-high lighting, lots of fast growing plants, and effective CO2 injection. If you do try this method without all of these “requirements”, it’s quite likely that the initial fish will be exposed to toxic ammonia and nitrite levels.

Asta e… mai aveam 3 zile, batusem tot ce stiam in materie de magazine si eram decis sa nu ratez vizita in strainezia fara sa-mi cumpar instalatia de dioxid.

Aveam destui cunoscuti in tara care aveau pet-shopuri sau firme prin care puteam sa fac import dar am vrut sa vad cu ochii mei ce cumpar si asa sa si evit clasicul adaos comercial pus de magazinele noastre la care, ca de obicei, se adauga taxa de Romania ( nu am inteles niciodata cat de mult vor astia de la noi sa se imbogateasca ..bagand niste preturi mai mari ca la magazinele de afara pentru niste oameni care nu au nici a 10 – a parte din salariile vesticilor … ma rog chestie de marketing).

In principiu, marile orase (cel putin ale din Germania), au la margine depozite de dimensiunile unui Metro, cu acvarii, accesorii, pesti, samd cu pretzuri mai bune …totul e sa ai masina ca sa ajungi pana acolo, daca nu, ai toate sansele sa iei la picior magazinele …iar eu nu aveam masina. Asa ca 2 saptamani am vazut cam tot ce era magazin in Berlin, am vorbit cu zeci de vanzatori (mult mai priceputi si mai doritori de discutii pe tema marfii pe care o vand decat cei de acasa ) si am aflat zeci de pareri despre diversele instalatii de CO2, intr-o tara care a inventat conceptul si care este suprasaturata de firme si aparatura in domeniu.
E drept ca nici eu nu plecasem ca un novice la cumparaturi …aveam o lista cu pretzuri pe diverse firme si stiam cu ce se “mananca” instalatia. De fapt aveam cumparate de prin anii 80 niste reviste Das Aquarium unde vazusem pentru prima data cum arata o instalatie de dioxid complet automatizata. Apoi prin ` 94 a venit un prieten din Canada care, alaturi de cateva plante de exceptie aduse (din cate stiu eu el a adus pentru prima data Glossostigma in Romania), ma innebunise cu tot felul de articole despre utilitatea instalatiei de dioxid. Nu ca as fi fost sceptic …dar conservatorismul imi spunea… merge si asa, fara. In fond ani de zile imi cresteam plantele cu apa paie si bataie, adica ceva lumini mai bune, 2-3 picaturi de solutii de fertilizare si un substrat cu turba iar in principiu chiar aveam rezultate bune. E adevarat ca mai aveam plante pe care le pierdeam ocazional dar cand vedeam ca asta este o meteahna generala nu ma impacientam prea tare si mergeam mai departe pe drumul si cu metodele clasice datand dinainte de `89.
Prima mea instalatie de dioxid a fost cu ani buni inainte totusi, tot clasica sticla de 2 litri de Coca Cola in care am aruncat niste drojdie ,ceva zahar, in capac am infipt etans un tub prin care iesea dioxidul dupa metoda atat de raspandita pe internet si in zilele noaste. Asa ca eu zic ca as cunoaste virtutile si neajunsurile magicei sticlute cu drojdie… care pe mine unul nu m-a convins. Pe post de bubble – counter foloseam un picator de la perfuzii iar reactorul era facut din sticla dupa o schema considerata de succes la vremea aia. Totusi concluzia mea este ca te chinui mult si fara de rezultate. Randamentul este inconstant si, ca la orice produs biologic si nu mecanic ,doua zile nu seamana una cu alta. De fapt nu poti decat masurand din ora-n ora sa afli cantitatea exacta de dioxid dizolvata in apa iar noaptea instalatia trebuie inchisa. Reglajul numarului de bule este si el, datorita presiunii variabile in sticla, un lucru anevoios, pentru ca trebuie sa tot stai cu ochii pe cum ai sau nu activitate … la drojdie. Daca o data ti-ai bagat prea brusc mai mult dioxid decat trebuie… pH-ul cade rapid iar Cryptocorinele care de regula sunt mai sensibile raman fara toate frunzele. In cateva zile iti poti distruge o munca de ani de zile si sa pierzi plante pe care poate nu mai ai de unde sa le procuri. Daca ai proasta inspiratie sa pleci de acasa si sa uiti instalatia artizanala deschisa… s-a terminat. Daca mai adaugi ca, in timp, datorita utilizarii unui furtun normal dinspre sticla spre reactor acesta se intareste in timp si devine friabil, dar si faptul ca reactoarele artizanale nu au eficienta celor de firma, avem un tablou mai complet. In plus, mai mult sau mai putin frecvent mai apare posibilitatea ca in timp, prin diverse blocaje, sa explodeze sticla. Solutia ar fi sa bagi mai putin CO2 ca sa fii sigur, dar atunci rezultatele nu mai sunt pe masura asteptarilor.

Sunt convins ca multi vor spune ca sunt carcotas, dar mie imi place sa ma bucur de pasiunea mea, nu sa-mi complic existenta si sa dau rateuri, in plus, pentru ca aportul de CO 2 sa fie eficient, acesta trebuie sa fie constant si in cantitati sensibil egale zi de zi. Inchei prin a spune ca schimbul de apa necesar pentru operatiunea de curatire a unui acvariu atrage de la sine o modificare a parametrilor fizico-chimici si deci o munca suplimentara in atingerea cantitatii optime de dioxid dizolvat, necesara bunei dezvoltari a plantelor.>
In concluzie, eu unul am abandonat ideia acestui tip de instalatie, acceptand necesitatea de a plati o suma ceva mai mare, dar avand certitudinea unui lucru bine facut. Fara a avea un motiv anume pentru care sa conving acvaristii sa imi imbratiseze ideile (uneori mai costisitoare) am gandit ca in fond o instalatie artizanala, daca era asa de eficienta, ar fi inlocuit de ani buni variantele de firma mai scumpe, daca erau intr-adevar eficiente!

Odata aceasta experienta consumata, am trecut la observatiile legate de calitatea diverselor firme producatoare de instalatii de CO2. Pana sa cumpar am analizat produsele existente pe piata germana ale firmelor Tunze, Ehaim, Sera, JBL, Tetra, Denerlle si in final, parintii conceptului … cei de la Dupla. In general din firmele mentionate instalatiile de la JBL erau cele mai ieftine iar cei de la Dupla si Ehaim cele mai scumpe. Intr-o piata cu concurenta reala insa, pretul ridicat ascunde calitate asa ca am inceput sa elimin pe rand … Tunze erau buni dar lucrau mai mult aparatura pentru acvariile marine. Cei de la JBL erau prea putin fiabili, la Sera nu am gasit niciodata instalatia completa samd. Pana la urma mi-am cumparat o instalatie de la Dupla, influentat si de ideea unei patroane de magazin care tocmai renuntase la instalatiile produse de aceasta firma… Din acest motiv am luat aparatura la jumatate de pret. Motivul pentru care se renunta la firma Dupla era ca, fiind foarte bune, sunt scumpe, iar ea isi dorea sa vanda repede marfa de pe raft.

Cum articolul se adreseaza mai ales celor care sunt decisi sa isi cumpere o instalatie dar care nu au vazut una si vor sa cunoasca … cum functioneaza si la ce se inhama, voi trece razant pe langa explicarea utilitatii acestei instalatii punand accentul pe componentele sale, pe aspectele tehnice si pe modul in care functioneaza. Poate voi reveni intr-un articol viitor, destinat celor deja initiati, cu date legate de modul in care se reflecta din punct de vedere chimico-biologic aportul de CO2 in viata plantelor de acvariu, in valorile pH-ului si kH-ului. Ideea de baza este ca plantele submerse isi acopera necesarul de carbon din dizolvarea CO2 in apa din acvarii, pe timp de zi. Cum acest lucru putea sa fie usurat prin ceva… a aparut aceasta instalatie care este compusa din mai multe elemente :

• Butelia
• Reductorul de presiune
• Bubble counterul
• Reactorul
• Tester vizual de CO2
• Valva electro-magnetica
• pH Controlerul cu sonda

BUTELIA

Recipient de obicei confectionat din aluminiu, dotata cu un robinet, frecvent dimensionata la 500, 750 si 1500 de grame la firma Dupla, prevazuta cu strat anticoroziv interior. Butelia suporta o presiune de 250 bari.
Butelii similare fabricate in Romania, pe dimensiuni mult mai mari, se gasesc si la noi in tara. Spre exemplu o fabrica de profil exista la Buzau. Este unul din produsele care nu necesita sa fie cumparate neaparat de la o firma anume, atat timp cat poseda un certificat de garantie si o inspectie tehnica bianuala autorizata care sa dovedeasca cum ca, nu s-a cumparat in fapt o butelie uzata . Am gasit in Romania, la sfert de pret, butelii excelente de 10 kg, cu o inaltime de 67 de cm, ce puteau fi mascate in dulapul de dedesubtul acvariului si care nu erau cu nimic mai prejos celor de firma. Am regretat faptul ca am cumparat varianta originala de butelie nu numai pentru ca as fi putut face o evidenta economie financiara ci si pentru ca buteliile germane au un sistem de incarcare ce nu este adaptat la cel romanesc si necesita confectionarea unei reductii . In plus, din experienta celor 4 ani de alergat dupa cei care incarca buteliile am observat ca aproape nimeni nu se complica sa umple recipiente mici, toti preferand buteliile cat mai mari. Un ultim avantaj al buteliilor de dimensiuni mari este faptul ca nu necesita incarcari frecvente si deci asigura o continuitate in procesul de imbogatire cu CO2. Am observat ca la o perioada de aproximativ o luna si doua saptamani, pentru un acvariu de 350 de l consumam o butelie de 750 de grame.

REDUCTORUL DE PRESIUNE

Reductorul de presiune, uneori denumit si detentor, ceea ce Dupla denumeste armatur, are, dupa cum ii spune si numele, functia de a reduce presiunea la care gazul este eliberat de la 250 de bari cat este in butelie pana la 1 bar. Cel de fabricatie Dupla este prevazut suplimentar si cu un reglaj fin de presiune, ceea ce usureaza eliberarea controlata a numarului de bule dorite. Asta nu inseamna ca asa ceva nu se gaseste si la noi in tara de fabricatie indigena, insa din pacate de cele mai multe ori fara a fi prevazute cu acest sistem de fine tunning necesitand ceva mai multa munca la reglaj… dar cu vointa totul este posibil. Exista reductoare de presiune care sunt dotate (atat Dupla cat si indigene) cu manometre ce indica presiunea in bari a gazului din butelie si cantitatea de gaz ramasa. Eu unul m-am dispensat de aceste accesorii pentru ca presiunea in bari la care poate fi incarcata butelia este perfect cunoscuta de cei de la centrele specializate in incarcare, iar cantitatea de gaz ramasa in butelie poate fi aproximata dupa ce devii experimentat in utilizarea instalatiei. In plus, de obicei sunt accesorii ce pot fi cumparate si adaugate in timp. Altfel, gandit dpdv. financiar, nu sunt chiar ieftine. Atrag atentia asupra faptului ca reductorul infiletat pe butelie, pentru etanseizare, are un O-ring fabricat din cauciuc de puritate ridicata care nu permite gazului sa iasa pe la imbinarea celor 2 componente de mai sus. De aceea, la fiecare incarare de butelie cand reductorul este scos, trebuie avuta mare atentie la modul de manevrare. Daca se scoate sau se infileteaza fortzat se distruge acest O-ring iar problema este ca desi O-ringuri de dimensiuni similare se gasesc in Romania, compozitia materialului este diferita si nu face fata la actiunea gazului. Nu sunt foarte scumpe, asa ca ati face bine ca atunci cand cumparati instalatia, sa va luati si cateva O-ringuri de rezerva.
Odata butelia incarcata cu CO2 de tip alimentar, gazul se transporta printr-un tub rezistent la actiunea distructiva a gazului (de obicei acest tub este livrat odata cu instalatia). Gazul intra intr-un bubble counter (numaratorul de bule) printr-o supapa ce permite ca CO2 sa intre dar blocheaza iesirea lui.

BUBBLE COUNTER

Bubble counterul este o piesa simpla dar foarte utila. Dupa cum ii spune si numele ajuta la numararea bulelor de CO2 pe care le introducem in bazin. Gazul este eliberat printr-un tub intr-un lichid (apa sau solutie parafinata) sub forma de bule, putand controla din fine-tunningul sau din robinetul buteliei cantitatea dorita de dioxid.

Este greu sa anticipezi numarul de bule necesar pe minut, dar in general se incepe cu un reglaj de o bula pe secunda si, in functie de necesitate, se mareste sau se scade numarul de bule. Firesc, nefiind un dispozitiv foarte complicat, este usor de confectionat si cu forte proprii, dar avand in vedere ca nici cele originale nu sunt scumpe si in plus faptul ca trebuie si aici respectate regulile de etanseizare perfecta, cred ca este mai bine sa il cumparati.
Gazul iesit din bubble counter este introdus spre destinatia finala prin acelasi tip special de furtun: in reactor. Pentru ca ar putea sa apara intrebari legate de furtun si materialul din care este fabricat, va spun ca se poate folosi pentru o perioada si furtunul normal de la vibratoare, dar acest furtun normal nu rezista in timp.

REACTORUL

Reactorul este una dintre cele mai importante componente ale instalatiei. Cu ajutorul lui dioxidul este dizolvat in apa sau mai exact, apa este imbogatita cu dioxid. Exista multe tipuri de reactoare iar mai recent au aparut chiar si reactoare externe care plimba apa prin dioxid imbogatind-o cu CO2. Totusi cele mai frecvent intalnite sunt reactoarele interne care au un orificiu prin care este introdus gazul, pe baza unor spirale sau zig zaguri in asa numitele cascade, si un alt orificiu mai mare prin care apa este introdusa la un jet slab prin intermediul unui power-head de putere mica. Apa astfel plimbata prin dioxid in cascade este imbogatita la concentratia dorita de CO 2 si elimita printr-un orificiu cu sita la baza reactorului. Cele mai performante reactoare (dupa parerea mea) sunt cele care au in interiorul lor plastic balls-uri ce ajuta la dizolvarea eficienta a CO 2 in apa. Eu spre exemplu, am ales un reactor de la Dupla cu o capacitate de difuzie buna la acvarii de pana la 400 de litri, in conditiile in care apa are are un dGH de 10 fabricat din Acrylnitril-Copolimer, in conditiile in care acvariul meu are undeva intre 300-350 l de apa.
Sunt trei factori care influenteaza randamentul reactorul de CO2:
1.       duritatea carbonata a apei din acvariu … cu cat duritatea apei din acvariu este mai mare, cu atat mai cantitatea de dioxd introdusa trebuie sa fie mai mare pentru a mentine o valoare dorita a pH-ului.
2.       cantitatea de apa ce curge prin reactor- cu cat curge mai multa apa, cu atat cantitatea de gaz dizolvata in apa este mai mare
3.       spatiu de difuzie- cu cat acvariul este mai mare, cu atat este nevoie de mai mult dioxid dizolvat

In plus, reactorul de tipul celui pentru care am optat mai are alte 6 orifiicii de reglaj al randamentului, amplasate pe o latura a reactorului, care ii permit sa lucreze cu un anumit randament dorit.

Nu vreau sa zic ca nu exista si reactoare facute de particulari care sunt eficiente. Chiar am vazut de curand niste modele de a caror eficienta ar putea fi convins chiar si un sceptic incurabil ca mine. Daca aveti posibilitatea sa gasiti un astfel de fabricant puteti scuti preturi de pana la 50 de euro… totul este sa stii pe mana carui fabricant te lasi, cat de multa experienta are in domeniu si de cand se joaca cu jucarii din astea. Dupla cred ca se joaca de vreo 20-25 de ani si eu nu am vrut sa-mi risc toata instalatia de dragul incercarii.

TESTER VIZUAL CO2

Pentru ca nemtii sunt oameni practici au gandit si un tester vizual usor de utilizat, care arata daca avem cantitatea de dioxid in concentratia potrivita in acvariu. Este util, usor de folosit si ideal chiar si pentru cei care inca vor mai avea de gand sa utilizeze clasica sticla cu drojdie si de acum inainte. Printr-un procedeu simplu se introduce apa din acvariu intr-un recipient special construit si 2 picaturi dintr-o solutie tester. Amplasat in interiorul acvariului, testerul se coloreaza instantaneu in una din cele trei culori diferite (de obicei galben, verde si albastru), in functie de cantitatea de dioxid din acvariu. Astfel stim ca daca culoarea testerului este verde am distribuit numarul de bule optim pentru plantele noastre si nu este nevoie sa marim sau sa micsoram cantitatea lor. Solutia din tester este inlocuita dupa fiecare schimb de apa din acvariu.
Aceasta metoda cu tester completata de o valva electro-magnetica conectata la o priza cu timer care sa permita un ciclu de functionare zi/noapte se poate constitui intr-o varianta manuala de ajustaj al instalatiei. E mai ieftina, insa necesita prezenta unui pH-metru electronic simplu de tip creion care sa indice cu exactitate pH-ul pentru ca, conform tabelului anexat, concentratii optime de dioxid se inregistreaza si la pH-uri mai mari sau mai mici decat cele ideale plantelor noaste. Astfel nu vom fi pusi in situatia sa distrugem plantele datorita pH-ului prea acid/bazic chiar daca concentratia de dioxid este optima.

VALVA ELECTRO-MAGNETICA

Valva electro-magnetica are un cablu conectat la 220 volti care poate fi conectata la o priza cu timer. Pe perioada zilei, cand plantele au nevoie de CO2 in procesul de fotosinteza, valva este deschisa prin alimentare cu curent electric si permite CO2 … ului sa fie eliberat din butelie.

Noaptea, cand prin programarea timerului, valva nu mai primeste curent, se blocheaza si nu mai permite gazului sa treaca, impiedicand astfel emisiile inutile si chiar in functie de cantitate, toxice, de CO2. Din experienta recomand ca valva sa fie deschisa cu o ora inainte de aprinderea luminii si sa fie stinsa la o ora dupa stingerea lampilor de iluminat. Acest interval recomandat insa, este relativ si poate fi dedus din vizualizarea testerului care, dupa cum am aratat, isi schimba culoarea.
Daca vreti insa ca lucrurile sa se petreaca cu o precizie matematica in acvariul dumneavoastra atunci este momentul unei alte investitii care cu siguranta va va transforma intr-un utilizator lipsit de griji, care poate sa uite ca are de facut ceva in directia dioxidului, caci totul este reglat automat cu un pH Controler electronic.

pH CONTROLERUL CU SONDA

pH Controlerul cu sonda masoara pH-ul si permite ca, odata reglata o valoare a acestuia, sa zicem in jurul optimului de 7 ( pH metrele digitale permit masuratori chiar si la 2 zecimale : 7,01 ) aceasta valoare sa ramana constanta. Se livreaza cu substante de calibrare pentru sonda (la valori de 4 si 7 unele si la 10) si controleaza electrovalva declansand astfel pornirea sau oprirea emisiei de CO2 automat, in functie de pH-ul dorit. Aceata valoare trebuie, dupa cum vedem si din tabelul cu concentratiile optime de CO2, doar corelata cu KH-ul apei din acvariu (ideal cu valori intre 4 si si in acest mod simplu se ajunge si la concentratiile optime de dioxid. Pretul este de aproximativ 200 de euro…e mult, e putin … depinde de cati bani, timp si pasiune avem fiecare. Dar mai ales depinde de taria de a depasi inertia lui las` ca merge si asa.

In principiu… nimic nu “merge si asa”! Articolul asta a fost dedicat unor colegi forumisti care se intrebau retoric de ce acvariile de prezentare vazute prin revistele vestice sunt acvarii de vis. De ce plantele vesticilor arata impecabil si aceleasi plante aduse la noi nu ridica mai mult de 2,3 frunzulite si apoi se distrug ? Tot ce pot sa va raspund este ca, investitia pe care o veti face cei cativa ( pe care sper sa ii fi convins) intr-o instalatie de CO2, nu este decat o parte din ceea ce are nevoie o planta ca sa arate la fel ca in revistele amintite. Ei au instalatii de zeci de ani, noi abia acum gandim cu mare efort sa cumparam. Daca ar fi inutile cum credeti ca acest produs s-ar vinde pe piata de 30 de ani avand componentele aproape nemodificate iar pretul scazut doar cu 500 de dolari. Ce vestic, care-si dramuieste banii mult mai pragmatic decat o facem noi, ar arunca banii in vant pe o instalatie inutila care iacata, supravietuieste nu ca un moft ci ca o necesitate de atata timp pe piata? Am zis ca o sa incerc sa dau un caracter mai tehnic articolului, dar in final nu ma pot abtine sa va lansez un avertisment de ordin botanic iubitorilor de plate de acvariu rare. Formele clorofil-deficitare ale plantelor scoase in laboratoarele unor companii de renume, ca Tropica sau Oriental Aquarium, etc la Anubias, Echinodorus s.a.m.d sunt plante superbe dar sensibile si instabile, care daca ar fi redate raurilor din care au provenit stamosii lor genetici, nu ar rezista. Ele, in fond, au fost selectionate pentru colorit, care chiar daca este placut pentru ochiul omului, este semnul de boala genetica si manifestarea a ceva nesanatos pentru planta. Aceste plante nu pot supravietui in conditii normale cum o fac altele. De aceea avertismentul meu se adreseaza celor care isi doresc astfel de bijuterii in acvariile lor si care daca tot cheltuie bani grei pentru a le achizitiona, trebuie sa stie ca le cumpara de pomana daca nu cumpara printre altele si o instalatie de dioxid.

Autor: Sandu Veres