This is our first spring having our pool. I am trying to figure out the best balance between letting the kids swim and killing our electricity. We have an electric heat pump, no gas. From what I have read, heat pumps cannot heat the water when the air temp is below about 50 Fahrenheit. My question - is it worthwhile running the heater overnight when the temp drops into the 40s? Even if it cannot heat the pool further, does it conserve energy vs turning the heat on mid morning when it warms up a bit?