Fluval U4 Clearmax Cartridge

Replacement PolyMax filter cartridge for Fluvals U series of internal filters. This helps 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 filter cartridge helps reduce overall aquarium maintenance. These cartridges should be replaced approximately every 4 weeks, each pack contains 2 cartridges. Sold in 3 different sizes for the U2, U3 and U4 filters.