Unlike natural aquatic systems, toxic compounds accumulate quickly in an enclosed aquarium system. Without a natural means to efficiently remove these toxic compounds, or wastes, conventional aquariums are dependent upon filtration devices. Filters help create a healthy aquarium environment capable of supporting life. Successful hobbyists understand the basics of aquarium filtration and rely on mechanical, biological, and chemical filtration to process and remove a wide range of toxic compounds.
Mechanical filtration is simply a method of straining out unsightly solids from the aquarium water. As the water passes through, the mechanical media physically trap and remove solids like plant debris, uneaten fish food, and fish waste from the water column. Mechanical filtration does not alter the water chemistry but merely removes solids from the water for a cleaner, clearer appearance.
Biological filtration involves a series of natural processes in which toxic ammonia is broken down by beneficial bacteria into less toxic components.
As colonies of beneficial bacteria consume ammonia, nitrite is produced as a byproduct. Nitrite is still toxic, but the good news is that a healthy aquarium also contains nitrite-eating bacteria that convert it into less toxic nitrate. Nitrate levels can be minimized in the aquarium through water changes.
Chemical filtration is the process of removing unwanted materials through chemical reactions. Chemical filtration helps remove a variety of impurities in the aquarium, including copper, chlorine, dissolved proteins, medications, discolorations, and tap water impurities.
For chemical filtration to be most effective, water should pass through the mechanical filtration portion of the filter first. This way, the particles reaching the chemical filter are less likely to clog the carbon.