SeaKlear PRS 2 Part ULTRA CLARIFIER , 2 Gallon Bottles Ultra-clarifying performance in easy-to-dose liquids Patented, 2-stage system Enhances filtration by trapping Cryptosporidium, E. coli, Giardia and Algae in the pool's filter Compatible with all pool filter media Two-stage system that keeps pool water clean and pristine Reduces waters turbidity and recovery time, especially during peak bather load Enhances the filters ability to trap particles down to 0.5 microns Removes oil better than the leading enzyme products Do not add both stage 1 and stage 2 at the same time