MarinePure bio filter media is designed to be a substrate for bio-filtration, specifically to target ammonia and nitrite removal (nitrification) and to minimize nitrates (denitrification). MarinePure is suitable for both freshwater and saltwater (marine) aquariums. MarinePure can be used fully submerged or in trickle/shower filters. It should not be used in moving bed filters. Size: 8x8x1 Plate