The filter is the unsung hero of your aquarium, quietly removing fish dinner leftovers, organic material, fish waste, and more insidious materials, like chemicals that can be harmful to sea life. As fish are swimming, they are perpetually producing waste. These toxins, excreted by the fish body, will eventually accumulate to a level that will kill the fish if they are not removed from the environment. There is even a name for this condition, called ammonia stress, and it can lead to ammonia poisoning. If your aquarium water appears clouded, that means you need a filter.
Aquarium Filters work on cleaning the fish tank in three ways
BiologicalBiological filtration, which involves a system of microorganisms and aquarium plants, involves “cycling.” Plants will process nitrogenous waste, but only while they are photosynthesizing in daylight.
MechanicalMechanical filtration involves a strainer, such as sponges, filter floss or filter pads, or biological materials, such as gravel or air bubbles.
ChemicalThe most common ingredient used in chemical filtration is activated carbon. This type of filtration will take care of impurities that other filters cannot handle. These may include toxins in the air that fall into the fish tank.