Fluval Foam inserts remove particulate wastes from the aquarium. They also provide many locations for beneficial bacteria to grow. Rinse the foam every few weeks for best results. Re-use of the foam can help protect bacterial colonies and provide continual biological filtration.

Fluval Foam 4pk. A-186. For the 4 Plus internal filter. These are the foam pads. The 4Plus also requires water polishing pads A-192 and the carbon pads A-197.