8 Mil thickness increases surface water temperature up to 10 degrees, extending your pool season enjoyment. Light blue cover color is a happy medium between heat absorption and retention Prevents evaporative heat loss during cool nights Cover cover should only be used when chlorine levels are below 2.5 ppm and pH levels are above 7.2. Using a solar cover reel provides more convenience when removing and applying the cover as well as helping to reduce wear and tear. In The Swim Solar Covers offer the ultimate heating potential and superb heat retention. An excellent and environmentally friendly way to capture energy from the sun and use it to heat your swimming pool. Designed for superior heat retention so your pool heats faster and stays warm longer. It has the capability to heat your pool water to keep your water warm longer so you can enjoy a relaxing and comfortable swim day, evening, or night. In The Swim Solar Covers feature UV stabilized resin construction and a unique bottom layer that helps transfer captured heat to your pool faster. These Solar Cover also act as an insulator and prevent the captured heat from escaping. It is also effective at reducing chemical loss that could be caused by water evaporation and help keep debris from falling into your pool, keeping it cleaner.