I see that the responses so far has been to run the pump at night to get cheaper electric. But when the nights are cooler do people think that they may prevent heat loss by not running the filter at night? My logic, is that in conjunction with a solar cover, a stagnate layer of water cools at the top and the water beneath stays warmer. Any thoughts?

FYI... at present I run 24 hrs/day, mostly because I have cheap municipal electric (about .03/kwh), but when the nights get cooler at the end of the season I will experiment with shutting the filter off at night to see if it helps save heat along with the solar cover.