Buying a pool cover that's slightly larger than your actual pool will provide the best protection and effectiveness. Choose a cover that will stretch about a foot or so over every side of your pool. A large cover will ensure that every inch is covered, and that there are no gaps for leaves or debris to slip in. If your cover is too small, it could sink into the pool and lose all effectiveness.

On the Other: Less is More

If you buy a smaller cover that's made with built-in air pockets, you can use less material, and still have a reasonable amount of coverage for your pool. The air pockets will allow the cover to float, which negates the need to attach the cover to the sides of the pool (which generally keeps it from sinking). While this just-big-enough cover does not protect your pool 100% of debris, it will allow some rainwater in. This way you don't have to waste extra water to fill up your pool. Also, this type of cover does a great job of trapping the sun's heat inside the water, saving money and energy when heating your pool.

Bottom Line

If you would like to be more environmentally friendly, the smaller floating cover is the way to go. If you are more concerned with keeping your pool water sparkling clean, it's best to get a little extra material for a cover that overlaps your pool edges, and can be secured tightly.

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Choosing a Pool Cover

Floating Covers

How to Choose Pool Covers