Aquarium Filtration Overview - Underwater Eco Systems

Aquarium Filtration Overview

Sometimes we forget that fish kept in an aquarium are confined to a very small quantity of water as compared to their natural habitats in the wild. In the wild, fish wastes are instantly diluted. But in an aquarium, waste products can quickly build up to toxic levels. These waste products include ammonia released from your fishes' gills, fish poop, and scraps of uneaten food. The food and the poop will also eventually decay, releasing ammonia. Even small amounts of ammonia will kill your fish.

Obviously, the more sources of fish waste, the quicker and greater the ammonia problem. A small heavily-fed tank with lots of large fish will have much more ammonia than a large tank with one seldom-fed small fish. But for both these cases you need some form of aquarium filtration to control the toxic ammonia.

Some aquarists try to control ammonia levels exclusively by changing the water. This is helpful, but impractical because of the frequency and size of the water changes required.

Fortunately, there is an easier way! In fact, the world is full of bacteria that want nothing more than to consume the ammonia and convert it into less toxic substances. For many an aquarist, this process occurs without their knowledge or help. However, the smart aquarist will learn how to take advantage of this beneficial bacteria by maximizing its growth.

When you start a new fish tank, colonies of beneficial bacteria have not yet had the chance to grow. For a period of several weeks this is hazardous to fish. You must gradually build up the source of ammonia (i.e., start with only one or two small fish) to allow time for the beneficial bacteria to grow. This is called ``cycling'' your tank.

Remember that the bacteria break down the ammonia into substances (first nitrite, then eventually nitrate) that are merely less toxic, rather than non-toxic. Many fish can tolerate reasonably high levels of nitrates, but over time the nitrates will accumulate until they, too, become toxic. Also, because nitrate is a fertilizer, high nitrate levels can lead to excess algae growth.