Hydro-Logic HL31027 Hydrologic Evolution Pre-Filter, High Capacity, Black Ensures your Evolution Reverse Osmosis 1000 system runs more efficiently Reduces filter changes to every 7,500 gallons Recommended when using more then 150 gallons per week Provides Two Extra Stages of Filtration Extends the Life of its KDF85 Catalytic Carbon Pre-filter From 2,000-Gallon to 7,500-Gallon Recommended for Systems Producing More Than 150-Gallon of Purified Water Per Week