Fluval Canister Filer 204-305 Foam Blocks do the important work of mechanical straining of particulate waste within the filter. This prevents waste from prematurely clogging other filter media in the module stack.
Features: Provides mechanical straining of particulate waste within the filter
Intended For: Hagen's Fluval Canister Filters
Rinse foam monthly in aged aquarium water and replace when the pore structure begins to break down.