5 Things to Know About Solar Pool Covers for Overnight Heat Loss

A solar cover (bubble wrap type) is the best option for preventing overnight heat loss. It traps heat in the water and, more importantly, cuts down evaporation, which is the biggest source of heat loss at night.

A solid thermal cover can also help, but it is heavier, more expensive, and does not let sunlight heat the water during the day. The bubble cover is cheaper, easier to handle, and does double duty: heats during the day and holds heat at night.

Thicker bubbles, around 12 mil or more, work better than thin ones. They provide better insulation and last longer.

Put the cover on before the sun goes down. If you wait until after dark, you have already lost much of the daytime heat.

Evaporation is the main cause of overnight heat loss, not just radiation. A solar cover reduces evaporation significantly, making it more effective than covers that only block radiant heat loss.