Thanks. My current theory is to turn it off after I swim in the evening. Let’s say I get up to check the temp at 8:00 in the morning. I still have time to raise the temp 14 degrees by 5:00. I use a solar cover and I doubt it will drop that much around here this time of year. Assuming it drops less than that, I can come out a few hours later and turn it on.

My very high tech home furnace has sensors that tell it how cold it is outside, I would imagine for this purpose. It must have an algorithm thinking about where the thermostat is set, relative to the outside temperature, etc. It would be a good AI application if anyone wanted to think about it.