Aquarium Supplies Sponge Filter Nylon fiber biochemical pad - Foam Media 1. It can be washed repeatedly. 2. The Biochemical Filter has the best effect on decomposing the excrement and the forage leftover. 3. The material has great thickness,it is durable. 4. This product can be used for sea water tank,fresh water tank and waterweeds tank with the sizes being cut as your wish