Paludariums (sometimes called River Tanks) are aquariums that contain both water and dry land. Paludariums are supposed to mimic a small patch of land beside a river or a pond. However, most paludariums contain a wide variety of plants and animals from all over the world and they really don’t mimic any real place. But that’s okay. A paludarium can be a place in your imagination for others to see and enjoy.
Despite its complex ecosystem and beautiful appearance, a paludarium is relatively easy to keep. If you have moderate skills at keeping house plants and freshwater aquariums or goldfish, you can be successful in keeping a paludarium. In addition to exotic tropical plants and fish, you may also keep various land animals such as geckos and frogs, though this is not recommended for beginners.
I have been keeping paludariums for about 7 1/2 years. During that time, I had tried a lot of things, some of them worked and some of them failed miserably. This article is a culmination of my knowledge in this field, presented as a step by step procedure on how I set up my latest paludarium. Even if you do not follow most of what I have done, I think you will find lots of useful information for your own design.
By the way, the entire project cost me $380 (U.S.) Dollars. Depending upon the size of the tank (the setup here is based on a 70 gallon tank), your costs may be higher or lower.
Start with an all-glass tank. Yes, I know acrylic tanks are the in-thing (the salesman will tell (sell?) you that they are seven times stronger than glass, one tenth the weight, etc.), but you will have the most success by using an all-glass tank. Acrylic tanks, due to their partially sealed tops will lead to uncontrollable „steam” on the inside of the tank walls as well as a variety of mold and mildew problems. They also tend to raise the inside ambient temperature.
You can buy „river tank kits” for standard aquariums but these are nothing more than plastic injection-molded „rocks” that look as bad as they sound. Some larger aquarium dealers will sell you a prefabricated paludarium setup, but plan on spending several thousand dollars if you go this route. The best thing to do is to order a custom tank from your dealer, but use the dimensions of standard tanks which will save you lots of money. The custom tank described in this article costs me $270. A prefab setup of a similar size sells for $2,250 at a local dealer.
I opted for a 70 gallon „tall” glass aquarium, which has the standard dimensions of 36 x 15 x 30. As shown in the dimensional drawing, my customization included a sheet of glass 13 inches tall set about 2/3 the way down the middle of the tank. This acts as the dividing wall that separates the water and land areas. I also had four holes drilled in the bottom plate for the associated plumbing, which will be used for filter input and output, land section drain, and wire chute. Drilling holes is optional, but makes for a much neater setup when you don’t have pipes and wires hanging down in plain view.
The back wall of the tank is what you will be seeing the most of when you look into your paludarium. You can use that cheesy paper background or the colored foil sold in aquarium stores, but if you want a realistic, natural look you have to use real materials.
The best thing to use is slate. It is light weight, it will not change the water chemistry, and will not discolor or absorb moisture. I went to a building supply place and bought about $10 worth of broken slate shingles, which did the trick. You can also try landscape supply houses or construction materials suppliers. You want to get it as thin as possible to keep the weight down. The slate shingles I used were about 1/2-inch thick. It’s fairly easy to shape slate, as it breaks cleanly using a hammer and cold chisel.
After shaping into irregular pieces, I glued each piece of rock to the background glass of the aquarium using silicone sealant. I used approximately one and one-half tubes of sealant. This material is very common and available at most hardware stores. The sealant cost me $4.39 per tube. Do not buy sealant that contains a mildew inhibitor. Make sure the label says 100% silicone sealant which when cured, is potable and safe for all aquatic life.
Be sure to wipe the slate and the glass with rubbing alcohol and let it dry before applying the sealant so you get a clean adhesive bond. You might want to lay the bigger pieces of slate down first (without glue) to see how things fit. It’s kind of like putting a jigsaw puzzle together. Use a hammer and chisel to shape the last pieces and make a complete fit. Slate breaks surprisingly easy, so it doesn’t take much force to make straight cuts. Also, you don’t need to glue any slate below the dirt level on the back wall, since the area will be covered from view anyway. Simply squirt a bead of glue on the back of each piece of slate and push it down on the glass.
The sealant will „skin over” in about an hour, but will take a full week to cure. Do not disturb the tank during this time. You may want to ventilate the area, because there will be a strong smell of vinegar as the sealant cures. This is normal. When the odor of vinegar in the tank is gone, the silicone sealant is fully cured.
The next step in the process is to fill the cracks between the pieces of slate so that the glue and glass do not show through. This is the process of applying mortar. Though we will not be using real cement based mortar, but common garden soil.
I used regular old dirt straight from the garden. I live in Southern California, where the dirt has a high clay content- perfect for this application. Gather some dry dirt in a pail, then pack it into all the cracks and crevices between the slate pieces. Use a toothbrush, stick, or small spackling knife to jam the dirt between and under the slate. Then, heavily mist down the entire surface with water using a general-purpose spray bottle. You will have a kind of slurry, muddy mess. This is okay. Continue pushing and adding more dry dirt into the cracks and crevices until no more dirt can be added. Let the whole mess dry overnight.
The next day, sweep away the loose dirt with a dust pan brush. You can now stand the tank upright. The photo shown to the left is the result. By the way, the photo doesn’t do this justice. The three dimensional look of the slate and mortar looks like some ancient cave wall. I’m also hoping that in time, I can get a tropical vine to climb along the wall and root in the dirt mortar. I have also thought about adding ground cover seed to the dirt mortar before packing it in the crevices. I’d be interested in hearing from anyone who tries this alternate method.
I had four holes drilled into the bottom glass. two for the filter intake
and outtake, one for a pass-through for wires, and one for a soil drain.
skip the filter holes and wire pass-through if you want, but you must have
some sort of soil drain. An alternative design is a dry well, where a length
of PVC pipe can extend above the soil level and essentially evaporate the
water that settles below the dirt level. However, this will only compensate
for small amounts of water. You will be amazed how much water settles in
the dirt section on the tank. Even without watering the plants, I typically
drain at least a half-gallon of water a week out of the soil drain. I’m sure
most of this comes from humidity and spills over the edge of the glass from
the water section. But in any case, be sure to include some sort of a soil
drain or after a while, your plants will surely rot away while they lose
the battle to transform into bog plants.
To adapt your drilled tank holes to your equipment, you’ll need PVC
It is a good idea to buy these at the aquarium store where your custom tank
was ordered, because you have to match up the outside hole sizes with the
manufacturer of the fittings. Otherwise, buy the fittings ahead of time and
take them with you when you order your tank. You also need PVC
ball valves for each
hole, which you can buy at a plumbing shop or a hardware store. Do not skimp
on these. I cannot tell you how many times a piece of tubing came loose while
working on the tank and the ball valve quickly stopped a potential torrent
of water from reaching the rug. Consider these safety valves, even though
you may rarely if ever use them.
The Land Section
For the land section, I first put in about 4 inches of lava rock. I
chose lava rock for its light weight, but you can use any kind of rock you
want. Next, I used
potting soil and filled the land section about an inch from the top of the
dividing glass. For the 30″ wide by 6″ deep section of this tank, it took
about 12 dry quarts of potting soil. I have not found any significant differences
between brands, so buy what ever is on sale. The photo to the
right shows the lava rock in place with the wires for the heater and grounding
probe coming out of the bulkhead for the wire.
The Water Section
the water section, start with a fine gravel. Do not use marine aquarium sands.
Use the smallest grain size gravel your aquarium dealer has for freshwater
aquariums. You may be tempted to go to a building supply house and buy gravel
for half the price, but be aware that many impurities (such as metal shavings)
may be present that will adversely affect your water chemistry. Pay the extra
bucks and buy it from the aquarium store.
You want a total of 5-6 inches of gravel depth. Start by adding two
inches of gravel, then add some garden soil or clay dirt to a depth of ¼
to ½ inch. This will provide a rich medium for your aquatic plants.
You may also add some gravel conditioners such as
Tetra’s Helena Initial D, which
I highly recommend. If you’ve added any water so far, the tank now looks
like a mud puddle. Don’t worry, it will clear up once you get some circulation
There are probably more debates about filter equipment
any aspect of the aquarium hobby. The short and sweet answer here is to use
a canister filter. I used a
but any reputable manufacturer’s filter will do. I have had a paludarium
set up in the past using a wet-dry filter, and do not recommend these. Even
if you use DLS material instead of Bio-Balls, you will still have a severe
CO2 outgassing problem which means that your aquatic plants will
be very unhappy. The „hang-on” variety of filters are not suitable for
paludariums due to the water level not present at the top of the tank. But
the good news is that your filter can be much smaller than you think. For
example, the 70 gallon tank used in this setup only holds about 20 gallons
of water, so you can get away with a smaller and less expensive filter. The
same holds true for the water heater.
You needs lots of light. Don’t settle for the standard aquarium light
and hood combos. For this setup, I used 4 20-watt fluorescent bulbs. You
can buy the ballasts at a hardware store and end caps at the aquarium store
and wire them up yourself. But if you’re electrically challenged, go to an
aquarium store that specializes in reef setups and buy a multi-bulb reef
fluorescent fixture. You might be able to find something at a hardware or
lighting store, but stay away from the so called „shop lights” because they
severely limit light output and bulb life.
Stocking the Tank
or Novaqua, then let the tank run for at least three days. Clean out the
filter which will probably be full of mud from the initial gravel placement.
Clean the polyester filter material and/or put in fresh material and let
the tank run for another day.
Go to your local nursery or garden center and look for small tropical
plants, typically in 1 to 3 inch pots. Ask the
personnel to recommend plants that like to be moist and do best in partial
sun or full shade. There are an incredible number of house plant varieties
to choose from. Some plants that do exceptionally well are the China Doll
Radermachera, English Ivy Hedera helix,
Pothos Epipremnum aureum, or the Bird’s nest fern Asplenium
nidus. Many ground covers (such as Baby’s Tears, Soleirolia
soleirolii) will also do exceptionally well. You can also add pieces
of driftwood and attach a variety of tillandsias. You should water once a
week (with aquarium water) and mist every few days. Drain the excess water
out of the soil section a day or so after watering. On a monthly basis, you
with a weak solution of Miracle Grow or other balanced fertilizer. Try not
to get any of the fertilizer solution in the aquarium water, which could
cause an algae bloom.
For the water section, choose community fish that will not disturb aquatic
plants. Most tetras and mollies fall into this category, as well as the „algae
eaters” (plecostomas) and many catfish varieties. Definitely ask your
aquarium dealer for help in choosing fish that are safe for a planted
As far as aquatic plant selection is concerned, you are limited by the
varieties available in you local aquarium store. Plants with darker leaf
colors usually require less light and will do better in the long run. A good
start might be anacharis elodea canadensis or Carolina Fanwort
Cabomba caroliniana. Fertilize plants weekly with a good liquid fertilizer
designed for aquatic plants or use the many tablet forms that can be placed
under the gravel near the roots. Choose a fertilizer that is high in iron
and contains no phosphates or nitrates.
To enhance the beauty of your tank, consider buying a small fog machine
(shown in action below). These little devices sell for about $40 and add
a tropical rain forest look to your tank. You can purchase one from most mail
order houses, which
also carries a variety of other accessories for your paludarium.
Sursa: Joe Jaworski