Oksale Aquarium Fish Tank Biochemical Small-Sized Sponge Filter Filtrator Percolator XY-2835 With an airlift system, super biochemical sponge filter features silent operation, and has an excellent filtering effect while oxygenating the water. The special developed foam materials support the colonization of bacteria growth. It allow for mechanical filter in addition to biological filtration, which will break down harmful waste, ammonia and nitrite material. It result in a cleaner living environment for fish, particular they are useful for as breeding filter or as secondary filter. Easy maintainence is made by nodular design of foam cartridge system. Fit for 10cm ~ 80cm deep fish tank