Pool Turnover Rate Calculator

Formula used

Volume (rectangular): V = L × W × D
Volume (circular): V = π × (D/2)² × depth
Volume (oval): V = π × (L/2) × (W/2) × depth
Turnover time: T(min) = Volume ÷ Flow, then T(hr) = T(min) ÷ 60
Turnovers per day: N = (Flow × 60 × 24) ÷ Volume
Required flow for a target turnover: Flow = Volume ÷ (TargetHours × 60)

Units are converted internally to US gallons and gallons per minute, then shown in multiple unit systems for convenience.

How to use this calculator

Pick a pool shape or choose Manual volume.
Enter depths. Use shallow and deep when applicable.
Enter dimensions, or provide the known volume.
Enter flow as total flow or multiple pump rates.
Set runtime and a target turnover for sizing.
Press Calculate and review the turnover outputs.
Download CSV or PDF for submittals and QA logs.

Always confirm design requirements for your project scope. If codes or specifications differ, follow those documents first.

Example data table

Scenario	Shape	Dimensions	Depth	Flow	Runtime	Turnover time	Turnovers (24h)
Community pool	Rectangular	40 ft × 20 ft	Avg 5 ft	60 GPM	24 h/day	~8.3 h	~2.9
Hotel pool	Oval	30 ft × 16 ft	Avg 4.5 ft	45 GPM	18 h/day	~5.6 h	~4.3
Splash pool	Circular	Diameter 18 ft	Avg 3.5 ft	30 GPM	12 h/day	~4.6 h	~5.2

Example outputs are approximate and depend on unit conversions and rounding.

Turnover rate and water quality control

Pool turnover time links hydraulics to water quality goals. A faster turnover supports consistent filtration, better chemical distribution, and more stable disinfectant residuals during peak bather load. For example, an 18,000 gallon pool at 60 GPM turns over in about five hours. If runtime is limited to 12 hours, the system achieves roughly 2.4 turnovers per day, guiding operational planning during peak season and special events. In construction planning, turnover targets also influence equipment selection, pipe sizing, and electrical capacity. Use turnover results as a planning checkpoint, then confirm performance with pump curves and flow readings.

Volume inputs that most affect accuracy

Volume drives every outcome in a turnover calculation, so measurement discipline matters. For new builds, take dimensions from approved drawings and use realistic depths, especially where floors slope. If the pool is irregular, use a surveyed or manufacturer-provided volume. Conversions between gallons, liters, and cubic meters are handled automatically, but accuracy starts with correct base geometry and depth selection.

Flow verification beyond nameplate ratings

Flow rate should reflect delivered flow at operating total dynamic head, not just catalog values. Head losses from fittings, filter loading, heater pressure drop, and elevation changes can reduce field flow. Where multiple pumps exist, ensure the selected pumps run simultaneously before summing flow. For commissioning, record flow readings, valve positions, and filter differential pressure to support repeatable operation.

Sizing decisions for runtime and energy use

Turnover can be achieved through higher flow, longer runtime, or both. Extended runtime may improve skimming and mixing while reducing peak electrical demand, especially with variable-speed pumps. This calculator reports turnovers per day and turnovers during your actual runtime window, helping teams compare operating strategies. Pair the results with energy models and local requirements to finalize control schedules.

Documentation for approvals and handover

Owners, inspectors, and facility operators often require clear turnover documentation. Exporting CSV supports submittals, design reviews, and as-built records, while the PDF report provides a concise snapshot for site files. Include assumptions such as depth basis, unit system, and whether flows were measured or estimated. Good documentation reduces disputes and speeds up acceptance during project closeout.

FAQs

1) What is pool turnover time?

Turnover time is the time needed for the circulation system to move a volume of water equal to the pool’s total volume through the filtration loop, based on the delivered flow rate.

2) Does a shorter turnover always mean cleaner water?

No. Turnover supports filtration and mixing, but outcomes also depend on bather load, filter performance, hydraulics, chemical control, and maintenance. Use turnover as one design and operating metric.

3) Should I use average depth or shallow/deep depths?

If the pool slopes, shallow and deep depths usually estimate volume better. If depths are uniform, use average depth. When reliable volume data exists, manual volume entry can be the best choice.

4) How do I handle multiple pumps?

Enter each pump’s flow rate only if they operate together in the same circulation mode. If pumps alternate or serve different features, calculate each mode separately using the corresponding flow.

5) Why might measured flow differ from design flow?

Actual flow changes with total dynamic head, filter loading, valve settings, and equipment condition. Always verify flow at commissioning using a flow meter or validated measurement method.

6) What should I submit with a turnover report?

Include pool volume basis, flow basis (measured or estimated), pump configuration, runtime assumptions, and the required turnover target from the project specs or authority having jurisdiction.