A solar cover will add weeks to your pool season.

Yes. A solar cover (that bubbly blue tarp) is the single cheapest, most effective way to warm your pool and push your swim season into spring and fall.

It works by trapping sunlight and preventing evaporation. Evaporation is the main way pools lose heat, especially at night. Put the cover on when nobody is swimming, and you can gain 5–10°F over a week of consistent use. That’s the difference between “chilly” and “actually enjoyable.”

You don’t need to buy some fancy automatic reel system. A manual cover and a cheap reel from Amazon will pay for itself in one season. The downside is the hassle of taking it on and off. If you hate that, get a liquid solar blanket instead—it’s a chemical that forms a thin layer and cuts evaporation by about half. Less effective, but zero labor.

Either way, solar covers work. Just don’t expect miracles in October if you live in Minnesota.