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The Classroom
Aquarium
by
David Watson
(Chapter 2)
Recently, while pruning the plants in one of our home aquariums, a school of baby lemon tetras darted from their grassy hideout into the open to investigate the intruder. To my astonishment, they swam around my fingertips before disappearing back into the thicket. Apparently the adult lemon tetras my son and I had purchased some months prior found our tank an enticing place to spawn. Their offspring escaped from being a morsel for the resident discus, as they would in nature, by dipping and darting among the vegetation.
It’s discoveries like this that make a planted aquarium ideal for the classroom.
In preparing for Mrs. Feeney’s 5th grade class aquarium project, I wanted our approach to be as simple as possible. Having the students participate in the initial design and set up, and the eventual care and maintenance were my main goals. There are many different ways to set up a planted aquarium. However, by following a few basic principles, anyone can turn an aquarium into a successful aquatic ecosystem.
Equipment
Mrs. Feeney’s classroom had a 55-gallon aquarium and was equipped with a heater and an appropriate canister filter. We outfitted her aquarium with the most important piece of equipment for a planted tank, proper lighting. A janitor was nice enough to install some chain link from the ceiling and we hung a shop light with 2 full spectrum fluorescent light bulbs. Our light fixture was plugged into a simple timer allowing for 12-13 hours of light.
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Filters play a different type of role in the planted aquarium than they do in the traditional aquarium. Filters provide water circulation and help in removing the solids from the aquarium. Remember the plants will be utilizing many of the waste products filters are designed to remove. Most importantly, the proper filter must not agitate the water surface or create bubbles (like a bubbling air stone) because surface agitation causes the removal of carbon dioxide (CO2). As you will see later, C02 has an important role in plant growth.
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Activated carbon, a common component of most aquarium filters, should be removed following the first 2 weeks after set up. Activated carbon removes toxic compounds, but also nutrients necessary for plant growth.
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Proper Lighting is especially important in a planted aquarium. There are many ways to accomplish this successfully. Fluorescent lighting is probably the cheapest and perhaps the most effective lighting. Many aquarium companies manufacture hoods with fluorescent lighting or it is possible to make your own lighting apparatus as we did with parts from a hardware store. The rule of thumb is to provide 1.5-3 watts per gallon. If setting something up from the hardware store, it might be a good idea to involve your custodial staff for suggestions.
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Substrate
The substrate serves several important purposes in our project. One, it provides a media for the roots of the plants to attach and grow through. Secondly, the substrate captures and holds the nutrients necessary for plant growth. Finally, it acts as a place for bacteria to grow, which are important in the aquaria ecosystem for degradation of biological waste.
We used three different components for our substrate: #40 Red Flint, a small gravel used in water filtration, Profile, a baked clay product used for planting water lilies, and black topsoil, commonly found at any hardware store. Before the set up day, I washed the gravel and made a 50:50 mix of the Profile and topsoil. My plan was to put ½ inch of Red Flint gravel on the bottom of the aquarium followed with 1 inch of the Profile/ topsoil mix and finally topping off the substrate with 2 inches of the Red Flint gravel.
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Substrate types are numerous. The basic foundation should involve an aquarium gravel with a size between 1-3mm. Though you could rely on fish food as the tanks sole nutrient source, I have had the most success using additives. Some additives such as laterite and topsoil will provide plants with the necessary nutrient of iron. Profile and other baked clay products have a high Cation Exchange Capacity allowing the nutrients to be captured and held by the substrate until the plants are ready to utilize them.
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Water
Knowing the type of water you have in your area may be one of the keys for success in starting your tank. By testing your water, you can avoid algae problems and give your plants and fish an optimal environment to live in.
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The water in the Evansville area is very hard (high in calcium). Also, the phosphorous levels are on the high side. Knowing that most aquatic plants from South America live in soft water, I decided to use a mix of 50% hard, tap water and 50 % deionized, soft water for the aquarium. By using this combination I hoped to decrease the phosphorus levels and minimize the outbreak of unwanted algae growth. Mrs. Feeney provided the deionized water from the chemistry department.
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Water kits are available from most pet stores. The following are four basic tests that I run on a regular basis: General Hardness (GH), Iron (Fe), Nitrate (NO3) and Phosphorus (PO4). Knowing the values of these parameters will help in determining if you need to soften your water, add hardness, or if you’re lucky, do nothing at all. Also, these kits will become useful when you start to manage the nutrients in the tank.
Nutrients
Unlike the traditional aquarium, a planted tank requires regular doses of fertilizer to sustain plant growth. The fish and fish food will provide some of the necessary nutrients, and an iron based trace mineral fertilizer will add additional nutrients beneficial to the plants. I planned on using Kent products for this purpose. Also, I constructed a CO2 fermentor to provide carbon for optimizing plant growth.
Nutrients
When adding fertilizer into any aquarium, it’s a good idea to use your test kits to monitor and maintain proper nutrient levels. The following are a basic guide of levels to maintain:
Nitrate (KNO3) 10-20 mg/l
General Hardness (GH) 6-10 dH
Iron .15-.25 mg/l
Phosphate (PO4) .2-.5 mg/l
When starting a new tank, it’s unnecessary to add any fertilizer for the first couple of weeks. Also, it’s a good idea to use the lowest recommended dose when starting and increase the proportion as plants begin growing and use up the nutrients at a more rapid rate. Starting slow and building up nutrient levels will help in avoiding algae problems.
Adding carbon dioxide (CO2) into a planted tank will greatly stimulate plant growth. Carbon dioxide fires the plants photosynthesis machinery resulting in the visible bubbling of oxygen that the class will be able to readily see.
CO2 can be added into the tank by using commercially available units, which use compressed CO2, or you can construct a simple fermentation device using sugar and yeast to provide the same effect.
Discus hiding in Sagittaria and Red Tiger Lotus
Plants
A few days prior to the set up, I acquired a nice selection of plants donated by Mr. Glaeser. The plants include: Vallsineria, Ecinodorus Sp. (Amazon sword plant), Sagittaria subulata, Rotala, Anubias, Microsorium pteropus (Java Fern), and Myriophyllum.
After sorting the plants, I was ready for the big day.
Chapter 3
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