Filter Bags are the most convenient form of mechanical filtration in aquariums with sump. Mechanical filtration will retain fine particles, excess of food, detritus, organic waste, dust, and other particulates. Removing these particulates from the water column will reduce the amount of organic matter that produces ammonia and other undesirable substances in the aquarium letting it with CRYSTAL CLEAR WATER! Elos Filter bag also helps to prevent larger objects, such as sand, crabs, snails, etc. from damaging the pumps of your sump.