Keep it at 78°F.

78°F (25.5°C) is the sweet spot. Warm enough for most swimmers to enjoy, cool enough that your heater isn’t running constantly.

Most recreational pools sit between 78°F and 82°F. Competitive pools are usually cooler (77-80°F) because swimmers generate body heat. For a backyard pool, 78°F works for both comfort and efficiency.

Every degree above 78°F adds about 10-30% to your heating costs, depending on climate and pool size. So if you’re swimming and think “it’s fine,” you’re saving money. If you need it warmer for kids or seniors, 80°F is okay but you’ll pay for it.

For energy savings, the real trick is a cover at night. That alone can cut heat loss by 50% or more.

You don’t need a spa – 78°F is the number.