OK, I have a solar bubble cover, and I use it in the spring and fall. But, during the summer here in Austin TX, I would like to slow down the evaporation rate of the pool without heating it up. Just solar heating with no cover usually keeps our pool between 83 and 89F. If I were to keep the solar cover on, the water would quickly become too warm for comfortable summer swimming. There is a nearby pool guy that sells 4'X4' pieces of thin, white foam (looks to be about 3/8" thick) for $15 each--it is not rigid, but probably originally comes on rolls, like the kind used for package cushioning. Good idea, but I suspect the wind would easily catch them--that would be a mess.
Anybody ever seen the 60" round "sun ring" style solar covers, but with a reflective surface (instead of transmissive) which would presumably stop solar heating as well as evaporation? Maybe a few of those on the pool would help. BTW, I understand after reading this forum, that the liquid stuff is pretty much useless, especially when windy.