Pool turnover calculator
Turnover is how long the pump takes to move one pool’s worth of water through the filter. It tells you whether a pump is big enough and how long to run it each day.
The formulas
turnover hours = pool gallons ÷ pump GPM ÷ 60GPM needed = pool gallons ÷ target hours ÷ 60
A 20,000-gallon pool turned over in 8 hours needs 20,000 ÷ 8 ÷ 60 = 41.7 GPM. A pump moving 50 GPM through that system turns it over in 6.7 hours.
Use the real flow. Pump labels quote flow at low resistance; the filter, heater, pipe runs and valves reduce it. A flow meter on the return line is the best answer, the pump curve at your system pressure the next best. The pool turnover guide explains run times and variable-speed pumps.
Questions
What is a good turnover rate for a pool?
One turnover in 8 hours is a common target for residential pools; public pools often must turn over in 6 hours or less under local code.
How many hours a day should a pool pump run?
Long enough for at least one turnover — often 8–12 hours at low speed with a variable-speed pump, which filters as well and uses far less power.