Do you use a solar cover during the day to heat the pool or at night to keep the heat in the water or use it all the time if you are not swimming in the pool?

Leave the solar cover on - day and night. During the day, cover will absorb the heat from the sun and transfer that heat directly into the water. At night, the cover will help to retain the heat absorbed during the day and reduce evaporation. Hope this helps ...

The original purpose of a solar cover is the ability to have the sun (err, solar) heat the pool thru the cover. If the cover is off during the day and on at nite you've wasted a $100+. C'mon, lets use a little common sense.