Aqueon QuietFlow Bio Ceramic Rings Filter Media is biological filtration that improves the overall water quality for fish. The porous surface area is ideal for beneficial bacteria growth for a healthier aquatic environment. Safe for use with freshwater or saltwater applications this filter media can be used with various fish tank filters including hang-on-the-back, internal, canister and sump. For use with freshwater or saltwater applications Improves overall water quality for fish Ideal for beneficial bacteria growth Can be used with various fish tank filters