Fluval BIO-FX is a premium biological media designed for use with canister filters and sumps of all sizes, including Fluvals flagship FX series. Featuring a deep pore structure with interconnected micro-tunnels, Fluval BIO-FX offers a vast surface area where billions of beneficial nitrifying bacteria can thrive. The three-dimensional linked cavities permit water to flow freely and evenly through the Fluval BIO-FX nodes, discouraging blockages while prolonging contact time for superior and effective biological filtration. Fluval BIO-FX supports an active nitrogen cycle: allows for the establishment of a high concentration of nitrifying bacteria to reduce ammonia and nitrite quickly and efficiently for a healthier aquarium.Fluval BIO-FX -Bio Filtermedium-+ biological filter media for fresh water and marine water+ safe, inert ceramic material+ designed for use with sump filtration and canister filters of all sizes+ especially suitable for the large Fluval FX filter series+ dimension of t