Fluval Canister Filter 404/405 Foam Blocks provide mechanical straining of particulate waste within the filter. This prevents waste from prematurely clogging other filter media in the module stack. Its primary purpose is mechanical filtration, but biological activity will also occur within the pore structure.
Features: Effectively strain particulate waste
Intended For: Hagen's Fluval Canister Filters
Size: 404/405 Foam Blocks
Rinse foam monthly in aged aquarium water and replace when the pore structure begins to break down.