The Merlin Garden Pro Sediment Prefilter (HydroLogic 22090) filters dirt and sediment from water, to prevent damage to your carbon Prefilter and reverse osmosis membrane. The sediment filter also reduces scale, rust and turbidity. Replace your HydroLogic 22090 filter cartridge regularly to ensure continual filtration and maximum efficiency of your system. The HydroLogic Reverse osmosis sediment Prefilter fits the Merlin Garden Pro Water Filter System. Reduces sediment and dirt for cleaner water. Designed specifically for well water (non-chlorinated water sources). Helps extend the life of the reverse osmosis membrane.