thanks mark..i will report back tomorrow morning the closing temp tonight based on it being heated up versus temp in the morning. given we are still going to swim in it for the next 3 days, i can't turn the heater off and want to maintain the temp for now, but it will be interesting to see if the heater can maintain that 85 temp with a cold overnight temp (cover on) or if it's going to have lost some ground. i would be very surprised if it's under 80 by tomorrow morning, even with heater cycling and cover on..we'll see!