Specifically designed for Fluval Spec Aquariums, Fluval Spec Biomax, 2.1 ounces, provides critical stage three biological filtration. Fluval Spec Biomax has a large surface area that provides optimal colonization of beneficial bacteria, which enhances the elimination of fish wastes, resulting in a healthier aquarium environment. The Fluval Spec BioMax has more capacity than most biological filter media and allows ideal water movement throughout the media, to ensure optimal contact time for efficient biological filtration.