Preparation and Maintenance of a Planted Aquarium With a Nutrient Rich Substrate
Step 1 – The preparation of the substrate/soils
Since plants grow much better in nutrient rich substrates ideally soils should be used. (E.g. potting soils, commercially available aquarium soils)
Soils also support various beneficial bacteria (chemoautotrophic, heterotrophic) which are involved in the decomposition of organic compounds, nitrification/de-nitrification, reduction and oxidation of heavy metals and gasses into plant nutrients. This means that using plain sand or gravel would be a poor choice for establishing a proper environment for aquatic plants especially in Low-light Low-tech aquariums.
In aquariums the soil should be approximately 4cm (1.5 inch) deep and covered with 4cm of sand or gravel which is 0.5-2mm in size.
There is another thing that should be considered before covering the soil with gravel. Not all tap water is the same. In the case your tap water is on the soft side (low levels/concentrations of Calcium, Magnesium and Bicarbonates) mix some crushed Dolomite or Calcium carbonate with the soil.
Ca/Mg Carbonates will prevent the acidification of the aquatic ecosystem and will provide the plants with Ca and Mg. Bacterial activity slows down under very acidic conditions (pH3-pH5) and by adding Dolomite the carbonates will create a buffering capacity.
Also metal oxides will become way too soluble when exposed to very low soil pH causing metal toxicity to plants (iron, aluminium).
In the case your tap water is hard there is no need for mixing Dolomite with the soil.
4-8 GH is soft
8-12 GH is medium hard
12-18 GH is fairly hard
18-30 GH is hard
Most plants prefer water hardness of 6-10 dGH.
NOTE!!! When suggesting the use of nutrient rich substrates I don’t mean Fluorite or commercially available substrates which are mostly rich in Iron (Fe). I suggest the use of soils which provide most of the macro and micro nutrients required for healthy plant growth.
E.g. the potting soil I use in some of my tanks is very rich in nutrients.
It contains N, P, K, Mg, S, Ca, Fe, Mn, B, Cu, Zn, Mo.
Once the soil is covered with sand or gravel add de-chlorinated water to the tank. NOTE! Add just enough water to saturate the substrate.
The tank should not be submerged yet!!
This part is very important!
Potting soil (or commercial aquarium soil) is terrestrial (exposed to O2) and has to go through a very sudden change. Once saturated in water O2 levels decrease rapidly used up by the bacteria.
Bacteria use O2 during organic decomposition. At the start the soil once submerged will release lots of nutrients into the water column.
The soil has to settle down before flooding the tank. With this method we can avoid unnecessary algae blooms and water turbidity.
Keep the soil saturated for 1to2 month. Note! Do not flood the aquarium yet. Add more water if it evaporates because the soil must remain submerged at all times to convert (soil cycling) into a settled aquatic soil which the plants require. It is important to wait to ensure sufficient bacteria development involved in nitrification of Ammonium to Nitrates, avoiding NH4/NO2 spikes which are very toxic to fish and crustaceans.
For those of you planning to use CO2 this is the perfect time to start planting. Many plants can grow emerged if substrate is saturated in water and humidity is kept high.
To keep the humid environment; seal the tank (some air can be allowed to enter of course).
Suitable plants for such emerged method are:
Hemianthus calitrichoides Cuba, Glossostigma, Marsilea sp., Eleocharis grass, Cryptocoryne sp., Microsorum, Anubias sp., and even Java/Christmas Moss.
This method also known as the “Dry Start Method” by Tom Barr is best suited for creating a foreground carpet. E.g. Hemianthus Cuba (HC) needs 4-8 weeks to fully cover the foreground.
Keep lights on for 12 hours to encourage plant growth.
This planting method doesn’t suit Low-Light Low-Tech aquariums because the plants are exposed to atmospheric CO2 during the emerged stage. Once flooded the CO2 is cut off almost immediately
and plants will start melting in a matter of days. (e.g. Cryptocoryne sp). And for this particular reason this emerged planting method suits CO2 injected aquariums (High-Tech) perfectly.
Once the plants are submerged they get all the CO2 via the pressurised CO2 system (25-30ppm) and no melting will occur.
I presume that aquariums where Excel or Easy Carbo (instead of the CO2 gas) will be dosed can also try this “Dry Start” planting method.
Photo 1 – day one of the emerged method (HC)
Photo 2 – eight weeks later
After approximately 2 months it is really worthwhile waiting, the tank can be flooded. Once the aquarium is filled with water, flush it out!
We do this because the nutrients which diffuse out of the soil into the water column might cause unnecessary algae blooms.
If you are extra cautious you can repeat the flush-out a few times. There is no harm in doing this but the water must be dechlorinated before adding it to the tank.
NOTE; never add ice cold tap water back into the system. It should be tepid to start with. Set the heater to approximately 26’Celsius.
At this stage introduce all the plants you want to grow. It is best to plant heavily from the submerged start. Also it is good to plant lots of rooting plants. Plant roots will add Oxygen into the rhizosphere to protect themselves from heavy metal toxicity and also by doing this the O2 enables the oxidation of the very toxic Hydrogen Sulfide gas (H2S) converting it to harmless salt HSO4 and the oxidation of Methane gas to CO2 and water. The plant roots will prevent soil Redox from becoming too low.
Step 2 – Water Circulation and Surface Agitation
It is of great importance to create sufficient water circulation and surface agitation in a planted Ecosystem.
Circulation will evenly distribute nutrients making them available for plants and bacteria. Aim for a circulation between 5-8 x of the tank volume per hour depending on plants grown and fish kept. Some prefer stronger currents while others weaker ones. Some aquatic gardeners use circulation of up to 10 x the tank volume per hour but they do reduce the water flow by using very long submerged spray bars which should be placed just below the surface.
Surface Agitation will insure sufficient gas exchange and will prevent the surface film from forming. Even though plants will provide lots of O2 through photosynthesis especially in CO2 injected systems it can’t hurt to add extra O2 via the surface agitation.
One should bear in mind that Oxygen is one of the most important electron acceptors involved in animal and bacterial metabolism.
At higher temperatures O2 levels decrease especially during the summer. When the temperature gets higher it is beneficial to create a strong surface agitation or add another power head for this purpose only. I have found that it is not the temperature that affects the fish/shrimp/plants during summer months but rather the low O2 levels. At higher temperatures the bacterial metabolism accelerates and uses up lots of O2 for nutrient recycling.
E.g. I live on the top floor and during the summer time the temperature of my tanks do go up to 31’Celsius. In the past I believed that this would harm fish, shrimps and plants. Now I know better. What I do under such extreme conditions is that I create a very strong (but no splashes) surface agitation in all my aquariums for good gas
exchange and I never experience any problems with fish/crustaceans or plants.
In planted aquariums keeping good Oxygen levels is as important as keeping good CO2 levels.
Step 3 – Finding the balance between lights, CO2 and nutrients
Because of people like Tom Barr, Greg Watson and Diana Walstad aquatic plant growing isn’t that difficult anymore.
Thanks to them aquatic gardeners have a better understanding about plant requirements and because of that we are able to grow healthy plants without deficiency symptoms and/or algae blooms.
For healthy growth plants require Carbon (C), Oxygen (O), Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Sulphur (S) as the Macro Nutrients and Iron (Fe), Manganese (Mn), Zink (Zn), Copper (Cu), Boron (B), Nickel (Ni), Chlorine (Cl) and Molybdenum (Mo) as the Micro Nutrients.
In comparison to the Micro-nutrients plants require larger amounts of Macro-nutrients.
Macros and Micros can be added via commercially available products like Tropica’s AquaCare Plant Nutrition N&P+traces and Seachem’s Flourish macro and micro fertilisers as well as dry fertilisers like KNO3, KH2PO4, Epsom salts, etc…
It is all about finding the right balance between the lights, CO2 and nutrients.
I have to draw a line here! There is a difference between dosing nutrients to an aquarium with only a few plants and heavily planted aquarium.
Plant density and plant growing rate is something to consider before deciding on the nutrient dosing methods.
Remember that there is a huge difference between dosing and over-dosing with nutrients. Dosing strategies are generally suggested for use in heavily planted aquariums were nutrient uptake is high!!!
Everything starts with the light. One can decide between using Low lights, Medium or High lights over the aquarium.
The light strength affects the plant growing rate. The stronger the light the faster the plant will grow and the faster it will up take the nutrients.
Deciding which light levels to use depends entirely on the aquatic gardener’s life style and goals.
Planted aquariums are complex and dynamic ecosystems, which hugely depend on us (the aquarist).
Nature doesn’t have much influence on them, and for that reason we are the ones pulling all the strings in leading them to an algae free/thriving planted ecosystem.
Plants need stable nutrient levels to thrive and grow lush. It is up to
the aquarist to understand the planted aquarium ecology and influence this system by finding the right nutrient balance.
Aquarium plants can be successfully grown in several ways and most of it depends on the light. This is simple mathematics;
The stronger the light, the faster the plant will grow, and the nutrient uptake will be greater.
Less light = slow growth = slow nutrient up-take.
Aquarium light levels:
Low lights are between 1 – 2 watts per gallon (0.3 – 0.5 watt/litre)
Medium lights are between 2 – 3 watts per gallon (0.5 – 0.8 w/l)
High lights have 3 watts per gallon or higher (0.8 w/l or higher)
How to calculate the light level:
Divide the total aquarium light wattage with the aquarium volume (gallons or litres) to get the light level per gallon/litre.
e.g. Lets say the aquarium is 48 gallons (180 litres) and has 2 x 30 watt fluorescent tubes.
2×30 watt = 60 watts in total over the aquarium
60 watts divided by 48 galls = 1.25 w/g, or
60 watts divided by 180 litres = 0.33 w/l
meaning this is a low-light set-up.
Common planted aquarium methods are:
Low-light (non-CO2 injected) planted aquariums, where soils are used as the plants’ main nutrient source. This is a low maintenance method, which requires very few water changes.
Low-Light planted aquariums where CO2 is used to stimulate the plant growth. This system will depend on extra fertilising and often water changes to stay in balance
High-light planted aquariums were CO2 is injected to stimulate the plant growth. Higher light levels provide plants with a huge amount of energy promoting luxurious lush plant growth. This is the common method used for creating stunning looking aquascapes; (Aquascaping Competitions)
Which method suits me best? you might ask
This depends on your goals and your life style.
1. Lets say you have a very busy life; long working hours, studying, kids, etc… and don’t have much time left for often aquarium water changes.
In this case, it is best to choose the Low-light Low-tech planted method, which needs only 5-6 water changes per year. For Low-tech tanks I dose nutrients once a week e.g. Tropica Plant Nutrition+ (read
plus) which contains NPK and traces 5ml per 50 litres. Even though plants can get most of the nutrients via soils we have to bear in mind that soils will become exhausted after approximately 6-12 month. To prevent this from happening it is beneficial to dose macro and micro nutrients via dry or liquid fertilisers once a week.
2. You have a tight budget, but would like to create a nice looking aquascape. Choose the Low-light High-tech method, meaning less light, less nutrients, inexpensive DIY/Yeast CO2 solutions, etc…
For this method I dose Tropica Plant Nutrient N & P + traces 1-2 times a week followed by a weekly 50% water change.
3. Or, your goal is to create a stunning looking planted tank for an Aquascaping Competition. In this case High-light High-tech method would be the best option. But to succeed in creating such a system, one has to dose nutrients often and do large weekly water changes to prevent nutrient over-dose. The best nutrient dosing strategy is known as the EI (Estimative Index) which was invented and popularized by Tom Barr.
For my 160 litres High-tech heavily planted aquarium with up to 0, 8 watts per litre I dose as followed:
*CO2 approximately 4 bubbles per second monitored via Drop Checker (25-30ppm).
Tuesday – (after the 50% water change) 1/2 teaspoon of KNO3, 1/8 teaspoon of KH2PO4 and 1/2 teaspoon of GH-Booster.
Wednesday – 10ml of Tropica Plant Nutrition for traces
Thursday – 1/2 teaspoon of KNO3, 1/8 teaspoon of KH2PO4
Friday – 10ml of Tropica Plant Nutrition for traces
Saturday – 1/2 teaspoon of KNO3, 1/16 teaspoon of KH2PO4
Sunday – 10ml of Tropica Plant Nutrition for traces
Monday – I dose nothing
With Tuesday it starts from the beginning (50% water change and nutrient re-dosing as followed above).
NOTE: Just remember, unbalanced planted tanks will lead to algae bloom, so e.g. choosing the High-light method, but not performing often water changes/plant pruning/nutrient dosing will lead to algae heaven.
Carbonate Hardness (KH) should never be under 4KH. Carbonates and Bicarbonates have the acid binding capacity. Carbonate Hardness level which is under 3KH doesn’t have a very good buffering capacity and therefore pH might shift drastically. If necessary dose Bicarbonates (Baking soda) to increase the KH.
Most plants can grow under all 3 light conditions if CO2 is not the limiting factor. For example it is believed that Hemianthus calitrichoides Cuba (HC) needs high lights to be able to grow into a foreground carpet. This isn’t true! This plant will do just fine under lower light conditions as soon as the CO2 is not a limiting nutrient. In CO2 limited systems HC like many other plants will grow upwards trying to reach over the water surface where the atmospheric CO2 is available. Many believe that plants grow towards the surface to get closer to the light source which isn’t true.
The most common reason behind plants growing like this or simply melting away is due to the limiting CO2 factor.
Of course under low lights plants will grow slower but with good CO2 levels they will eventually grow into the desired aqua-scape.
Step 4 – Aquarium Hygiene and Plant Maintenance
Once the aquarium is maturing organic matter starts accumulating creating mulm, filters get clogged with particles, and plant bio mass increases to the point where tank maintenance becomes necessary.
With each water change it is good to perform light substrate vacuuming just over the gravel. No need for deep vacuuming in planted aquariums with many rooted plants. Like this we keep the beneficial Oxidizing Microzone (top layer of substrates) from becoming anaerobic (clogged with mulm).
The Oxidizing Microzone helps to convert toxic NH4 to NO3 and it keeps nutrients trapped in the substrate (oxidation).
Filtration will remove floating particles and help in nutrient recycling. External filters seem to work best in planted aquariums. One of the reasons they are a better choice than inner filters is that they keep all the collected dirt outside of the tank. Once the filter is opened for cleaning, all the dirt stays in it. On the other hand when taking the inner filter out of the tank for maintenance half of the trapped dirt leaks straight back into the aquarium. This should be avoided and for that reason external canister filters and hang on back filters (HOB) should be used.
Clogged filters will reduce circulation. Clean them regularly. How often depends on the pump type (external, inner) and fish bio-load.
When cleaning the filters make sure not to rinse them under tap water which contains chloramine. Such tap water can damage the beneficial bacteria living in the filter. Always rinse in aquarium water from the water change.
Under balanced nutrient conditions plants will grow better especially the fast growing stem plants. One should never allow them to grow to the surface. When this happen gas exchange becomes limited and low Oxygen levels might occur causing various issues e.g. algae, surface film, NH4/NO2 accumulation, stressed fish, etc…
Also, overgrown plants will reduce water circulation creating dead zones. Prune the plants regularly. This will not only encourage new growth but will make your plants look much better. The more you prune them the bushier they become.
Foreground plants should be mowed regularly. They tend to grow on top of each other creating a tick carpet. If the carpet is allowed to grow too tick it will start to rot from the underside and the whole carpet might float up (e.g. HC).
Partial water change is very important and should be performed weekly in Hi-tech and “Excel Only” aquariums. Like this we reduce excess nutrients which might have built up via extra fertilisation.
Hi-tech systems require frequent nutrient dosing (3x a week) and for that reason it is beneficial to do weekly water changes (50%) to re-set the system.
Low-tech aquariums require less water changes to prevent CO2 fluctuations. These systems need steady CO2 levels in accordance to avoid algae issues. Tap water is rich in CO2 and with each WC we add a fair amount of CO2 which plants will consume in just a day or two leaving them with low CO2 levels for the rest of the week. Fluctuating CO2 levels will very likely cause algae issues (stressed plants). For Low-tech tanks it is enough to do a 50% water change every 2 month. For that reason we rather under-stock with fish to minimize the organic build up.
Certain fish and crustaceans can also help a lot in maintaining hygiene in a planted aquarium.
One of my favourite is the Caridina multidentata shrimp (formerly C. japonica) which was popularized by Takashi Amano. This shrimp is a very effective Thread/Hair algae eater. Besides algae it will also help to recycle dead plant matter and fish waste, breaking it down to smaller organic particles which bacteria can consume.
This shrimp also feeds on bacteria and micro-organisms preventing them from over populating the system.
Malaysian Trumpet Snail is very effective in aerating the substrate’s top layer keeping the Oxidizing Microzone aerated. It spends most of it’s time digging through the substrate in search for bacteria, micro-organisms and dead organic matter.
Otocinclus catfish which grows to just about 5 cm is a very useful addition in planted aquariums. This tiny fish will clean plant leaves from Diatoms and bacteria film.
Siamese Algae Eater (Crossocheilus siamensis) is the most effective fish in eradicating the Black Beard Algae (BBA). It grows to approx 14 cm and for that reason is not suitable for smaller tanks (fish requirements)
Neritina sp. Zebra is another snail worth keeping. It is particularly effective at eating the Green Beard algae and Green Spot algae which tend to grow on rocks and wood. Remember not to stock too many because they will start laying white eggs all over the aquarium which can look unsightly to some people. These eggs can’t hatch in fresh water.
It is not that hard to achieve a balanced planted Ecosystem once you put certain things into perspective.
First of all find the right planted tank method, one which will suit your goals and your life style.
Cycle the soils by using the “Dry Start” method.
Plant heavily and stick to the dosing routine (right balance between the lights, CO2 and nutrients).
Prune the plants regularly and keep good hygiene (clean filters, light vacuuming and regular water change).
Rather under stock with fish (this will keep the organics low).
Stock the tank with fish and shrimps which will help removing organics and minor algae.
I compare the Aquatic Ecosystem with us humans. We need balanced diet, good hygiene and good environment to keep us healthy. The same can be applied to plants, fish and crustaceans.
Article written by Dusko Bojic
Photos by Dusko Bojic