Fluval Bio-Foam for FX4, FX5 & FX6 Canister Filters - 2 Pack

The Fluval Bio-Foam for FX4, FX5 & FX6 Canister Filters is a two-pack of Bio-Foam blocks cut for the FX4, FX5 and FX6 canister filters, which trap fine debris and also carry a large share of the filter's bacteria.

Key Features

• Traps the fine particles that get past the coarser foam, which is what gives water its polish
• Also a biological surface. Foam holds far more bacteria than people expect, which is why it should never be replaced wholesale
• Two blocks per pack, cut to fit the FX4, FX5 and FX6
• For use in both freshwater and saltwater aquariums
• Made by Fluval, the aquatics brand of Rolf C. Hagen, which has been building aquarium filters since 1975

Using It

• Rinse mechanical foam in a bucket of old tank water rather than under the tap
• Replace one block at a time and leave the other in place, so the bacterial population carries over
• Squeeze rather than scrub. Foam that has been scrubbed clean has been stripped of the film that does the work
• Never wash biological media in tap water and never replace it all at once. Chlorine kills the bacteria living on it, and changing everything together restarts the cycle

Good To Know

• Foam wears out eventually — it goes mushy and stops springing back. That is when to replace it, not when it looks dirty
• A clogged foam is the usual reason an FX filter loses flow
• A genuine Fluval spare part. Check the model number against your unit before ordering — Fluval part numbers look alike and do not cross over between series
• Check the model before ordering. FX2 foam is a different part