The primary chemical in heatsavr (Solar Fish) is isopropyl alcohol which changes the evaporation properties of water. Because a pool loses most of the heat through evaporation, this can help reduce heat loss as well. They claim as much as 40%. It is not as effective as a cover but a whole lot easier to use. I plan on trying it out this season to see how well it works.

Here is a web site that has the technical information:

http://www.flexiblesolutions.com/pro...ety_data.shtml