Your pool can lose inches of water per week just through evaporation. Sunheater Liquid Heat Shield helps your pool retain heat and reduces chemical loss by forming an ultra-thin, invisible barrier on top of your pool water that reduces evaporation. It's a non-toxic, odor-free solution that is 100% safe for both swimmers and pool equipment. Sunheater Liquid Heat Shield is easier to use than a solar blanket. There's no messing around with cumbersome blankets and reels, but it can still extend your pool season by keeping the water warmer for longer. Plus, it's easy to use. Simply add the amount designated for your pool size by using the easy-to-read marking on the bottle. Use just 4 oz for every 20,000 gallons of water.