Evaporation accounts for up to 70 to 80% of heat loss from a swimming pool. A single Ecosavr contains the liquid solar swimming pool cover which automatically floats to the surface of the pool and acts as an evaporation inhibitor, much as a conventional solar blanket performs, except a lot easier to use. Our key ingredient is a non-toxic chemical called Heatsavr, it"s been in use since 1991 and has a proven track record commercially. We packaged it to facilitate its application for the residential swimming pool owner. Heatsavr is filter friendly, does not affect the chemical balance (PH, chlorine, alkalinity) of the water, will not damage vinyl liners or any other pool surfaces, and is absolutely harmless to skin contact. Simply snip the fin where indicated and toss "Eco" in your pool. Ecosavrsubmerges to the bottom of the swimming pool and as the pressure increases, the liquid escapes, rises, and forms an invisible layer on the surface of the water. It is 60% as effective as a conventional solar pool cover but 100% less trouble. It works 24 hours a day, even while people are swimming. Ecosavr will last for approximately 1 month. Then all you have to do is retrieve "Eco" and toss a new one in. Filter friendly.