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Turnover Time Calculator

Estimate how long your pump takes to “turn over” the pool once.

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Use GPM if you know it (from pump curve, flow meter, or manual).
Estimated turnover time:
Important: “Turnover” is an estimate, not a guarantee of water quality. Chemistry (FC/CYA), brushing, filtration condition, and circulation patterns matter more than chasing a perfect turnover number.
Tips:
  • If your pool is clear and balanced, you can often run less.
  • If you’re fighting algae/cloudiness, run longer and clean the filter as needed.
  • Flow rate changes with dirty filters, valve positions, heater/SWG, and RPM (variable-speed pumps).
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Safety note: Always follow manufacturer guidance for minimum run time for heaters, SWGs, and freeze protection.

How the Turnover Time Calculator Works

This calculator estimates how long it takes your circulation system to move a volume of water equal to the total pool volume. Enter the pool volume and the actual flow rate in gallons per minute or liters per minute. The result shows the estimated time for one turnover and the amount of water moving each hour.

Turnover is a mathematical estimate. It does not mean every drop of pool water passes through the filter exactly once, because water mixes continuously and some areas circulate better than others.

Why Turnover Time Matters

Turnover time helps estimate pump runtime, filtration capacity, and whether the system can move enough water for equipment such as heaters and salt chlorine generators. It is useful for planning, but it should not be treated as the only measure of good pool care.

Clear water depends on proper chlorine, balanced chemistry, brushing, circulation patterns, and a clean filter. A pool can have a fast turnover and still develop algae if sanitation is inadequate.

What Changes Flow Rate?

Actual flow can change with pump speed, dirty filters, plumbing size, valve position, water features, heaters, salt cells, and other restrictions. A variable-speed pump may produce very different turnover times at different RPM settings.

Common Turnover Mistakes

  • Using the pump’s maximum advertised flow instead of actual system flow.
  • Ignoring pressure loss through filters and equipment.
  • Assuming one turnover guarantees clean water.
  • Running a variable-speed pump at one estimated flow for every speed.
  • Chasing extra turnovers when chemistry is the real problem.

Frequently Asked Questions

How many turnovers does a pool need each day?

There is no single number that fits every residential pool. Runtime should be based on sanitation needs, equipment requirements, water clarity, debris load, and energy efficiency.

How do I find my actual GPM?

A properly installed flow meter gives the best direct reading. Pump curves can also estimate flow when total dynamic head and pump speed are known.

Does a dirty filter slow turnover?

Yes. As filter pressure rises, system resistance usually increases and flow can drop.

Is longer pump runtime always better?

No. Once circulation and equipment needs are met, extra runtime may only increase energy cost. The goal is effective circulation, not running the pump simply to chase a number.

Pool Gal Pro Tip 💦

Use turnover as a planning number, not a pool-health score. If the water is cloudy or green, fix the chemistry and filtration problem instead of assuming more runtime alone will solve it.