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<BODY>The River Tank provides a cross-section view of a "river". The water circulates through the tank, flowing into and out of several pools of different water levels. Fish delight in swimming against the current streaming out of each pool. Using short bursts of speed and making a slight splashing commotion, the fish propel themselves up to the next level. As the water falls, the turbulence forces air into the water and eventually the tiny trapped bubbles slowly rise back to the surface creating an ebullient effect. The sight and sound of the rippling water and the activity of the fish creates an ever-constant state of motion that is fascinating to watch.
The Tank
This River Tank was created using a Rivertank Ecosystem kit. Originally, the River Tank was sold by FinnStrong Inc., the kit is currently marketed by Perfecto Manufacturing. They now offer a "New River Tank" kit that has a more natural design.
The kit consists of plastic inserts that are installed inside a glass tank using silicone sealant. The inserts divide the tank into separate pools and also provide hollow spaces and ledges above that can be filled with gravel to support land plants. The upper pool is 12 inches deep, the middle pool is 10 inches deep, and the lower pool is 7½ inches deep. The tank is 55 gallons (48"x21"x12"), but is filled with only approximately 20 gallons of water.
In the lower pool, a Penn-Plax Thresher Shark pump is submerged in the lower pool where the nozzle fits into the wall of the filter chamber. The filter chamber is designed to fit the extra large Whisper Bio Bags. There is a spill over channel at the top of the chamber that carries the water from the filter back to the upper pool. A submerged Tronic 100 watt heater located in the upper pool keeps the water at a constant 72° temperature.
I obtained my tank second-hand. The tank had been used for some time and needed to be cleaned. I removed the inserts from the glass walls using a razor blade and then thoroughly cleaned them and the glass. The plastic inserts had a mottled blue-grey color originally which I thought made the tank look very gloomy. Although I knew it would take some effort, I decided to cover each insert to improve the look. I bought clear aquarium safe silicone at the hardware store (GE 100% Silicone Rubber Sealant Widow & Door) spread it over each piece and then threw small-grain horticultural gravel on until each piece was entirely covered. The result was a plastic insert that looked like rock! It really made a great improvement on the appearance.
Land Plants
The land plants in the River Tank are ordinary houseplants purchased at a local garden store. I selected small plants in 2" plastic pots. I hadn't researched plants that prefer a well watered environment, but all the plants I chose are doing well. I took the plants from their containers, removed all the dirt, and planted the bare roots into the gravel. The plants are growing hydroponically, taking in nutrients from the water seeping through the gravel. The plants growing on the ledges are watered daily by hand because I prefer not to have a glass cover on the tank (which would increase humidity). The plants are thriving under the fluorescent lighting from the two 40 watt strip lights above. One of the polka dot plants actually bloomed purple flowers, something I had never seen before on these houseplants.
Some land plants in the River Tank:
Pink/white polka-dot plant (Hypoestes sanguinolenta)
Aluminum Plant (Pilea cadierei)
Nerve plant (Fittonia verschaffeltii)
Spreading clubmoss (Sellaginella kraussiana)
Asparagus fern (Asparagus densiflorus 'Sprengeri')
Aquatic Plants
The aquatic plants that are in the River Tank are those that don't require as much light. The strip lights are well above the surface of the water, therefore some of the plants requiring stronger lighting just didn't do as well (like Cabomba).
Some aquatic plants in the River Tank:
Rotala rotundifolia
Hygrophilia polysperma
Elodea canadensis
Dwarf crinum (Zephyranthes candida)
Narrow Leaf Chain Sword (Echindorus tennellus)
Fish
There is a diverse fish community in the River Tank consisting of:
8 Corydoras catfish (julii, paleatus, myersi, punctatus - 2 of each)
8 Tiger barbs (3 orange/black, 3 green, 2 blond)
2 Gold barbs
2 Pencil fish
14 assorted Danios (zebra, leopard, blue, gold)
2 Mystery snails and numerous pond snails (not fish but...)
The sleeker danios move effortlessly from pool to pool. The stocky corydoras are surprisingly strong enough to fight the current to make the jumps, but most prefer the security under the overhang in the lower pool. The two myersi corydoras remain exclusively in the middle pool, while the tiger barbs can always be found schooling together in the lower pool. Staying occupied fighting the current streaming into the lower pool from , the barbs don't have time to pester one another or other fish. One of the tiger barbs has figured out there is life beyond the lower pool and regularly explores the mid and upper pools. The gold barbs occasionally venture upstream. The danios are by far the most adventurous and entertaining to watch. I have found a few swimming in the channel where the water is pumped from the filter into the upper pool and in the filter chamber itself!
Danios, having a streamlined form and hyper nature, are the most active in the community, flittering from pool to pool.
I feed my fish an assortment of food: sinking wafers for catfish, shrimp pellets, flake food, spirulina flakes, mini floating fish pellets, floating food sticks, algae wafers, and frozen bloodworms. The tiger barbs, gold barbs, and danios all have bright, vibrant colors due to their constant activity and varied diet.
Maintenance
The maintenance of the River Tank takes a minimal amount of time. I try to perform a partial water change every week, changing approximately 4-5 gallons. An algae-pad scrubber is used to clean the the front of the glass. The Bio Bag filter, changed every two weeks with extra charcoal and ammonia chips added, keeps the water crystal clear.
The "River Tank":A Versatile Tool for Teaching Science
Build Your Own Living Eco-System
The River Tank
Perfecto Manufacturing
Laine Knowlden- e-mail: river_tank@yahoo.com
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