12 hours a day is usually plenty, but you can often get away with less.

Yes, 12 hours is the standard recommendation for a single-speed pump in summer. But if you have a variable-speed pump, you can cut that in half and still keep the water clear, because you run it at lower speeds for longer turnover.

The goal is to turn over your pool’s water once every day. Take your pool’s gallons, divide by your pump’s flow rate (in GPH), and that’s your minimum runtime. For most residential pools with a single-speed pump, 8–12 hours does it. If your water is sparkly, try backing off an hour each week until you see haze, then bump back up.

Running it longer isn’t bad, just costs electricity. Running it less risks algae.

If your pump is oversized or your pool is small, you might need only 6 hours. Test and adjust.