Bio-Foam Filter Media was designed exclusively to fit Fluval aquarium canister filters. Due to its dense structure， this filter traps small particles that are not captured in the first stage of foam filtration. The large pores provide an ample surface area that encourages the growth of helpful nitrifying bacteria， which is crucial for efficient biological filtration. Suitable for freshwater and marine environments， Bio-Foam Filter Media from Fluval helps to create clear and healthy water for fish and plants to thrive.