Dymax Bio Sphere is a highly porous media designed to be a substrate to bio-filtration, it removes ammonia and nitrite (nitrification) and reduces nitrate (denitrification) for freshwater, marine and reef aquariums. The Bio Spheres cultivate nitrifying bacteria on its outer sphere and denitrifying bacteria in the inner, therefore providing ability to eliminate toxic substrate and help to prevent algae growth. It is suitable for all filtration system types, particularly effective in a canister filter.