Hello- I live in M***achusetts, where it was about 80 degrees on Saturday. At 8 AM on Saturday, my pool water temperature was 68 degrees. I turned on my propane heater, and at about 2 PM it was 78 degrees, 5 PM it was 80 degrees, 8 pm when we left the pool it was 81 degrees. At that time I turned the heater off {not down}.The air temperature overnite went down to 53 degrees.

This morning {Sunday}, at 8 am, the pool water temperature was 78 degrees!
Today, at 2PM, the temperature in the pool was back to 81 degrees, without ever turning the heater back on. We swam until about 4:30PM.

I have not used my Solar Cover since the first Summer I got it 3 years ago, because, after observing the above type of heating/cooling cycle, and for the minimal amount of heat loss or gain that occurs, I also found that I dislike the crud that blows onto the cover, which would normally be collected in my skimmers, I dislike the reel because you need two people to do it right, and I dislike the circulation in the pool if you turn the eyeballs down.

So my lovely Blue Solar Cover sits at the ready up against the fence at the deep end of the pool, waiting to get called into the game.