Filtration: Necessary process to poison free aquarium water

In order to have poison free aquarium water the filtration process is a very importantone. Most aquarists are aware of the fact that their aquarium water gradually accumulates potentially harmful substances, which eventually poison their fishes. In order to prevent this from happening there is a need for filtration, therefore for this purpose I would define filtration as the removal of unwanted substances from water.

Most aquarist uses three types: Biological, mechanical, and chemical amongst which the biological is the most important.

Biological filtration is also referred to as undergravel filtration, because the major equipment used (a flat plate of perforated plastic) is placed under the gravel bed hence it is invisible. Unless you are properly equipped, you can’t see the process happening and cannot measure its effect. Yet this process is the major difference between success and failure, and the aquarist who does not take the time to understand it workings is doomed to watch an endless procession of dying fish passing through his tank.

Biological filtration is solely the work of bacteria attached to the surfaces of the gravel, the grave and the under grave filter together constitute the filter bed. Bacteria normally reach the filter bed through the food you give the fish, the waste product of the fish, the air, and even through your hands as you work in the tank.

As the water ages, the bacteria numbers increase until the gravel is loaded with millions of them. It is only then that the aquarium can function very well, because the wastes of the fishes and unwanted substances mainly ammonia are immediately broken down by those bacteria into harmless substances while at the same time the filtration action drags organic matter downwards into the space between the gravel where the roots of plants can then extract essential growth substances hence the undergravel filter promotes healthy plants growth.

Mechanical filtration is the physical removal of debris, waste products, uneaten food, dead fish or plants. They use a filter medium such as foam, filter wool or sand/gravel to trap particles which are removed by later cleaning of the medium.

Chemical filtration changes the composition of some substances in the aquarium. Ammonia absorbers, such as Ammogon tm help prevent problems when water aging is done chemically (treatment with chloramines releases free ammonia). Other "chemical" filtration includes ion exchangers which reduce either carbonate or sulphur hardness.