The Aquademics™ classroom aquarium has a closed filtration system.   This is a system in which the water in the tank is recirculated through filters and reused.

In all aquariums, no matter how large or small, it is of primary importance to provide the fish with environmental conditions that replicate, as closely as possible, those in the natural environment.  For example, the ordinary tap water that is used in a freshwater aquarium must be treated to remove chlorine or chloramine and other substances that are harmful to tropical fish.  Also, the water must be cleaned of normal wastes.  The process of keeping the water clean and safe is called filtration.

To optimize a fish's survival in the Aquademics™ classroom aquarium, students should understand the filtration process and also be concerned with factors such as appropriate water treatment, ammonia level, pH level, temperature and light.

In the Aquademics™ aquarium, there are three types of filtration at work:

• Biological Filtration is the conversion of nitrogenous wastes to less toxic nitrogenous compounds by the action of bacteria living on a suitable substrate such as a gravel bed that probably will be used in the Aquademics™ classroom aquarium.

• Mechanical Filtration is the removal of suspended particles from the water by some type of filter medium such as gravel and also through the fuzzy floss covering on the Whisper® Bio-Bag®.

• Chemical Filtration is the removal of dissolved organic compounds.  Dissolved organic material can cause the water to have a yellow appearance.  This is remedied using a carbon filter or a foam fractionator.  Some harmful compounds and medications can also be removed through chemical filtration.

In the classroom aquarium, the gravel bed provides a place for two aquarium bacteria (Nitrosomonas and Nitrobacter) to live.  Airlines and air stones circulate the water down through the gravel where the bacteria can convert the ammonia to a nitrate.  Food particles and other debris are also pulled down into the gravel.  To remove increasing nitrate levels and particles in the gravel, a percentage of water (usually 20 percent) is replaced about every two weeks in a small tank.  A water change also replaces essential trace elements that fish have used.

Reprinted courtesy of the National Aquarium in Baltimore