I have basically the same climate as msumoose, and my evaporation loss is very similar. The problem with solar covers in our climate is that, even without a cover at all, by late July the water temps are approximately bathtub warmth, and by August it's usually actually too hot to be comfortable swimming. I welcome the evaporation loss in my pool because it allows me to top off with tap water, which lowers the water temp of the pool enough to make swimming still fun.

Janet