Fluval U4 Poly-max Cartridge 2pcs

From the Fluval range. Poly-max, 2 in 1 filter cartridge which helps control green water & unsightly algae growth. Absorbs & traps phosphate, nitrite & nitrate to provide healthier, crystal-clear water. Effectively traps fine debris & contaminants. Helps to reduce overall aquarium maintenance. 2 pieces per pack. Designed for freshwater & saltwater. Replacement recommended every 2-4 weeks. U4.