Solar cover questions

[mskovrinskie]

I have a gas heater as well as a solar cover and my wife and I prefer pretty warm water (79 degrees). Gas is expensive and it is a pain to constantly take the cover on and off. I typically run the pump on a timer overnight and manually turn on when we are swimming in the day. The cover seems to work really well as an insulator for night but I'm not sure if it is better for heating during a sunny day or if just open sunlight works best. If I leave the cover on with a sunny day, I notice the first few inches of water is VERY warm, but underneath it is chilly. Is it better in that case to circulate the water while the cover is heating it?

 

[SCCS]

I say "If it is free use it."
I have a solar cover to, no gas heater. I leave the cover on all the time except when swimming and the pump run's from 2pm to 4pm to circulate the warm water near the cover with the colder water near the bottom. In the last few weeks my water has warmed from the 60's to 82 degrees.

 

[PaulR]

I also leave my cover on all day, because I'm more interested in reducing water loss through evaporation than in any heating effects. But I've also noticed the heating effect on the top couple inches on a sunny day. I expect circulating during the day would make that more effective; as you cool the underside of the cover, you increase the temperature difference, and you'll get more efficient conduction from the cover to the water.

That said, the overall effect is likely small. If you are trying to heat the pool for free, having the cover off during sunny days is probably the most effective method.
--paulr