How long does it take for solar cover to heat the pool

[Klutz14159]

I've been using a 12mil clear solar cover for the last two years, and based on my records, I think it adds about 5deg F to the pool temperature in the steady state during swim season. Due to pandemic, I also haven't been away from home for more than two days during swim season.

I was wondering if I take the cover off while I'm out of town and let trichlor pucks do their thing, when I get back in town and put the cover back on, how long does it take to reach steady state heating? Is it next day effect? or does it take a couple of days?

I've always been too afraid of losing heat to conduct the obvious experiment myself

 

[Newdude]

how long does it take to reach steady state heating? Is it next day effect? or does it take a couple of days

It's entirely dependent on the weather because no heating takes place. Instead, the solar cover stops the evaporation which is responsible for about 70% of your heat loss. It's seen tomorrow as a 'gain', but it's really just retention.

That's where the weather needs to be favorable because the cover will only keep it about 5 degrees above where it would have been. After 3 or 4 days of cooler weather, the pool is cooler too, even with the cover.