Compatible Fluval U3 PolyMax Filter Cartridges Phosphate Nitrate Foam Fish Tank Aquarium Filter You are purchasing Finest Filters Compatible PolyMax / ClearMax filter cartridges suitable for the Fluval U3 aquarium filter. Replacement PolyMax compatible filter cartridges for Fluvals U3 series of internal filters. 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, each pack contains 8 cartridges. Sold in 3 different sizes for the U2, U3 and U4 filters. Size (mm): 195 x 60 x 13
