Fish excrete waste constantly just like any other living things as they swim around the water. This waste is a potential poison to fish thus it's highly essential to find a way to remove this toxin from the aquarium tank.

The process of removing this excess food, decaying matters, dangerous chemicals, fish waste products and free floating particles from aquarium water is called filtration. And the tools use is called filter.

Filters for aquariums come in all sorts of shapes, types and sizes, but they perform the same basic function, and that is to circulate the water through some form of straining or cleansing medium at such a rate that the water is kept clean physically and biologically.

Filters are categorized as 'inside', 'outside' and sub gravel; based on the location around the aquarium, but the location is not as important as the way in which it operates.

The three major categories are mechanical, biological and chemical.

Mechanical filters remove unwanted materials from the water by straining and /or the use of absorbent materials. It helps maintaining water clarity doing so.

Biological Filtration: - Unlike mechanical filtration process biological filtration involves bacteria and other microorganisms converting your fish's waste into less toxic substances through a process call cycling. Biological filter will convert your fish's toxic waste ammonia into Nitrite, and from nitrite to nitrate, which is relatively harmless. This cycling reduces the required maintenance in your aquarium. Chemical filtration as the name implies can remove toxins and other chemically induced material from your aquarium system with the use of activated carbon. It's necessary to change activated carbon should be changed often to have a save community.

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