6 lbs New Bio Ceramic Rings in 6 Free Bags for Aquarium Fish Canister Filter by Brand new This listing is 6 bags of 1 lb premium Bio Ceramic Ring each ( 6 lbs in total) 6x Premier Bio Ceramic Rings in Bag 4 Aquarium Fish Pond Reef Canister Filters The ceramic material that these Bio rings are made of is extremely porous. They look solid, but actually there are millions of tiny holes in it. The surface area and tiny pores make it an ideal home for the cycle bacteria that you want in the filter. A good ceramic media will provide large amount of surface area for bacteria to grow. They are good to use for both fresh and saltwater aquariums.