A pack of 2 replacement bio-foam blocks for the Fluval external 104/105/106/107 filter.
Fluval Aquarium Filter Foam Blocks provide mechanical straining of particulate waste.
These prevents particulate waste from prematurely clogging other filter media in the module stack.
Although the primary purpose of Fluval Foam is mechanical filtration, biological activity will eventually occur within its pore structure.
These Fluval Aquarium Filter Foam Blocks also enhance biological filtration.