Super biochemical sponge filter features silent operation, and has an excellent filtering effect while oxygenating the water. The specially developed foam materials support the colonization of bacteria, allowing for mechanical and biological filtration, which will break down harmful ammonia and nitrite material resulting in a cleaner living environment for your fish. Particularly useful as a breeding filter or as a secondary filter. Will reduce noise from the air pump and consumes low wattage. Most fit to external or top filters as a pre-filtration unit. No dead spots in cylinder bio-chemical foam offering full filtration