Swimming Pools We get asked this question a lot here, pool cover on or off during the day, what is the best option? Normally if you want to keep your pool clean you would have installed a pool cover that is on the pool at night. Some of these are electrically operated so they are easy to open and to close. You can also set these on a timer to open and close at certain times. The issue most people face is what to do on a hot day? Is it better to leave it on or off if you want to heat your pool. Usually, if you cover up the pool, you can feel the top of the water is warm and the bottom will still be cool, but what happens if you leave it open most of the time to warm the entire pool. The theory is it would be heated by the sun, and guess what, it actually does heat the pool more. If you stop using your cover during the day it will heat all the way to the bottom of the pool. It will also heat the pool better if you leave your pump off during the day. Then you can close your pool cover at night so it doesn’t lose heat to evaporation! On a humid, calm or sunny warm sunny day, then open it up. On a standard 20×40 pool you can see around 6 degree gains on a very sunny day. Long story short, You’ll get a lot better heating with the cover off during a nice warm sunny day and retain the heat with the cover on at night. Other benefits of only using your cover at night time is the longevity of your pool cover itself. Without the sun blasting the cover all the time its going to be cheaper in the long run to have it open every day. If you are using a pool heater this will also reduce the amount of time you need it on as you will be starting from a higher base temperature. So really, there is no downside. I hope this helps you guys and if you decide if you should have your pool cover on or off during the day. If have any problems, simply leave a comment for us below!