Finest Filters 4 x Compatible PolyMax ClearMax Foam Filter Pads Cartridge With Fluval U4 Range of Internal

You are buying a pack of 4 compatible Polymax / Clearmax filter cartridges to fit the Fluval U4 internal filter. These help control green water and unsightly algae growth by adsorbing and trapping phosphate, nitrite and nitrate. It effectively produces crystal clear water, reduces odours, and creates ideal conditions for fish and plants. The polymax / clearmax filter cartridge helps reduce overall aquarium maintenance. These cartridges should be replaced approximately every 4 weeks. Replacement PolyMax compatible filter cartridges for Fluvals U4 series of internal filters.