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Pool Turnover Rate Calculator

Turnover rate is the time your pump needs to push the whole pool through the filter one time. This pool turnover rate calculator takes your gallons and your pump flow and returns the turnover in hours, the run time for a full day of filtering, and the flow you would need to hit an 8 hour cycle.

Pool turnover rate calculator illustration of pool water circulating through the filter in one full loop

Run the numbers

Formula used

Turnover Hours = Pool Gallons / (Pump GPM x 60)

Your result

Turnover time
6.00 hours
Run time for two turnovers
12.0 hours per day
GPM needed for target
37.5 GPM
Water filtered per hour
3,000 gallons

Results update as you type. Round up when you buy materials.

How the pool turnover rate calculator works

One turnover does not clean everything. Water mixes as it circulates, so a single pass filters about 63 percent of the volume. Two turnovers get you near 95 percent.

Commercial pools are held to strict turnover rules, often 6 hours or less. Residential pools do fine at 8 to 12 hours as long as the water stays clear and chlorine holds.

The formula, step by step

Turnover Hours = Pool Gallons / (Pump GPM x 60)

  • Take your pump flow rate in gallons per minute.
  • Multiply by 60 to get gallons per hour.
  • Divide pool gallons by that figure to get turnover time in hours.
  • For the GPM needed to hit a target time, divide gallons by target hours and by 60.

Worked example

An 18,000 gallon pool with a pump moving 50 gallons per minute.

50 x 60 = 3,000 gallons per hour.

18,000 / 3,000 = 6 hours for one turnover. Running 12 hours a day gives two full turnovers.

Watch it done

This short video walks through the same job in real life, so you can match what you see on screen to what you do at the pool.

Video guide: Pool Turnover and Pump Run Time by Swim University. Video hosted on YouTube.

Tips before you start

Use your real flow rate, not the box rating. Read the filter pressure gauge and the pump curve, or fit a flow meter on the return line for an honest number.

Split the run into two blocks if your pool gets heavy afternoon use. A morning cycle and an evening cycle keep skimming active across the whole day for the same total hours.

Pool Turnover Rate Calculator FAQs

What is a good pool turnover rate?

Eight hours is the common residential target. Anything under 12 hours keeps most backyard pools clear.

How many turnovers per day do I need?

One full turnover is the minimum. Two is better during hot weather or heavy swimmer use.

Does a slower pump speed hurt turnover?

It lengthens the turnover time but saves a lot of power. Run a variable speed pump longer at low speed and you still hit the same total volume for less money.

How do I find my pump flow rate?

Match the filter pressure reading against the pump performance curve, or install an inline flow meter for a direct reading.