First I will say how much we really like these! We had a bubble pool cover before and it was very difficult to use. We followed the directions, didn't over inflate these, and find them pretty easy to use and are keeping our pool warmer! We turned on our heater and placed these in the pool. We heated the pool to 84 degrees and turned off the heater. These have kept the pool at a pretty consistent 82! We stack them in the pool onto each other, which is not recommended by the manufacturer, but, it's easier for us. We just leave them floating in a pile. If we have a crowd, we hang them over a rounded top wall.