Pool Turnover Rate Calculator
Turnover rate describes how long a pump and filter take to circulate the pool's entire water volume once.
Enter Values
How to use this calculator
- Enter your pool's water volume in litres (use the Pool Volume Calculator first if you don't know it).
- Enter your pump's flow rate in litres per hour to get the turnover time, or enter a target turnover time to find the flow rate you need — or enter both.
- Read the turnover time, turnovers per day, and/or the required flow rate from the results.
How it works
Turnover rate describes how long a pump and filter take to circulate the pool's entire water volume once. The core formula is turnover time (hours) = pool volume (litres) ÷ pump flow rate (litres/hour). Dividing 24 by that time gives the number of complete turnovers achieved in a day.
To size a pump instead, the calculation is reversed: required flow rate (litres/hour) = pool volume (litres) ÷ target turnover time (hours). Manufacturer flow ratings are measured at zero head, so the real flow through your plumbing and filter will be lower — allow a margin. Actual filtration quality also depends on filter condition, circulation, and run hours, not turnover alone.
Worked example
50,000 L pool with an 8,000 L/h pump. A 50,000 litre pool circulated by a pump moving 8,000 litres per hour has a turnover time of 50,000 ÷ 8,000 = 6.25 hours, which is 24 ÷ 6.25 = 3.84 turnovers per day. Most residential pools aim for at least 1–2 full turnovers daily, so this pump comfortably keeps the water filtered.
Common mistakes
- Using the pump's rated (zero-head) flow instead of its real flow at your system's back-pressure — actual turnover is usually slower than the nameplate suggests.
- Mixing units: the volume must be in litres and the flow in litres per hour. Convert gallons or cubic metres first (1 m³ = 1,000 L).
- Assuming one turnover fully cleans the water. Because filtered and unfiltered water mix, a single turnover removes only about 60–70% of particles, so most guidance targets 1–2+ turnovers per day.
Frequently asked questions
What is a good turnover rate for a pool?
Residential pools typically aim for at least one full turnover per day, and many operators target two, giving a turnover time of 8–12 hours or less. Public and heavily-used pools are often required to turn over much faster (commonly 4–6 hours or less) under local health regulations — always check the rules that apply to you.
Does one turnover mean all the water is clean?
No. Filtered water returns to the pool and mixes with unfiltered water, so a single turnover removes only roughly 60–70% of contaminants. That is why guidance usually calls for one to two or more turnovers per day rather than just one.
Should I use the pump's rated flow rate?
The rated flow is measured at zero resistance. Your filter, pipework, fittings and any solar or heater add back-pressure (head), so the real flow — and therefore the real turnover — is slower. Size with a margin and, if possible, measure actual flow with a flow meter.
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- Pool Volume Calculator
- Water Tank Volume Calculator
- Flow Rate Calculator
- Irrigation Flow Calculator
- Litres per Minute to Cubic Metres per Hour Converter
- Pipe Flow Calculator
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