Fluval BIO-FX is a premium biological filter media featuring a complex porous structure with deep interconnected micro-tunnels. This safe, inert ceramic media provides a massive surface area for beneficial nitrifying bacteria, helping to efficiently convert ammonia and nitrite into nitrate. Designed for use in canister filters, sumps, or filter baskets (including Fluval FX and 07 series), Bio-FX supports superior biological filtration and long-term water quality in your aquarium.