Foam Block for Fluval 204, 304, 205, 305, 206, 306- 2 pk.

Fluval Foam Blocks provide mechanical filtration by straining particulate waste from your aquarium water before it can prematurely clog the chemical and biological media in the Fluval 204, 304, 205, 305, 206, and 306 Canister Filters. Fluval Foam is designed as mechanical filtration, but biological activity will eventually occur within its pore structure.

For more information on mechanical and biological filtration, please read our article on Aquarium Filter Maintenance.