Turnover is the time it takes to circulate your entire pool once through the filter. Enter your volume and pump flow rate to size your runtime.
Turnover time = pool volume ÷ (flow rate × 60). A pump rated at 60 gallons per minute moves 3,600 gallons an hour, so a 21,000-gallon pool turns over in just under six hours. Most residential pools aim for one to two turnovers a day; public pools are often required to turn the full volume over in six to eight hours. Running cost is the pump's power draw (watts ÷ 1,000 = kilowatts) multiplied by hours run and your electricity rate. If you know the wattage from the motor label, enter it for the most accurate figure; otherwise the tool estimates it from horsepower.
Two pumps of the same horsepower can move very different flow rates depending on your plumbing — pipe size, run length, fittings, and how clean the filter is all change the total dynamic head the pump works against. That's why this calculator treats horsepower as an estimate with a range, and lets you enter a measured GPM for accuracy. Variable-speed pumps add another wrinkle: they draw far less power at low speed than their horsepower suggests, so a horsepower-based cost estimate will overstate what a variable-speed pump actually costs. If you have one, run it slower for longer and enter its real low-speed wattage for a true figure.
A 24,000-gallon pool with a 50 GPM pump: 50 × 60 = 3,000 GPH, so 24,000 ÷ 3,000 = 8-hour turnover. To turn it over in 8 hours you need about 50 GPM of flow.