The CAF-10 is a simple, classic and economical sponge filter for beginner and advanced aquarists alike. The specially developed foam materials of each CAF sponge filter supports the colonization of bacteria, allowing for mechanical and biological filtration. The process breaks down harmful ammonia and nitrite material resulting in a cleaner living environment for your fish. The CAF-10 is weighted and used an airlift system for superior filtration and silent operation. The CAF sponge filters can be used as stand-alone filters, although many customers find them particularly useful as breeding filters or as a secondary filter.