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Aquarium Filter Turnover Calculator

See how many times per hour your pump or filter moves the whole tank volume.

✔ Vet reviewed · 18 Oct 2026Updated 18 Oct 2026Sources: Pure arithmetic / unit conversion on user inputs
Aquarium Filter Turnover CalculatorFree · instant
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L/h

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Quick answer A 200 litre tank with a pump moving 800 litres an hour is turned over 4 times an hour, or once every 15 minutes. Printed flow rates are for an empty hose, so real flow is lower once media and height are included.

How to use the aquarium filter turnover calculator

  1. Enter the tank volume.
  2. Enter the flow rate printed on the pump or filter.
  3. Press Calculate.

Worked example

A 200 litre tank with a filter rated at 800 litres an hour.

Tank volume
200 L
Pump or filter flow per hour
800 L/h
4 turnovers an hour
Tank volume
200 L (53 US gal)
Rated flow
800 L/h (211 gal/h)
One full cycle takes
15 minutes

Printed flow rates assume no lift or resistance, so real flow is lower once pipes, media and height are included.

Example values are illustrative; this result is produced by the same calculator above.

How we calculate it

turnovers per hour = flow rate per hour ÷ tank volume; minutes per full cycle = 60 ÷ turnovers per hour

Sources: Pure arithmetic / unit conversion on user inputs (no external constant)

Understanding your result

Turnover tells you how many times per hour the filter or pump moves the whole tank volume. Divide the flow rate per hour by the tank volume: an 800 litre an hour filter in a 200 litre tank is 4 turnovers an hour, one full cycle every 15 minutes.

Printed flow rates are measured with no resistance, so real flow is lower once media, hoses and lift are included. Treat the result as an upper limit.

The right turnover depends on your fish and filter type, so follow advice for your species. This tool tells you what your equipment gives.

Common mistakes

  • Using the filter's rating without allowing for blockage and media.
  • Using the tank's gross volume rather than its real water volume.
  • Mixing litres and gallons per hour.
  • Assuming a higher turnover is always better.
  • Forgetting to clean the filter, which lowers flow.

Good to know

  • Find the volume with the Aquarium Volume Calculator.
  • Some fish dislike strong currents.
  • Check flow again after cleaning or changing media.

Frequently asked questions

What turnover rate do I need?

That depends on your fish and filter type, so follow advice for your species. The calculator tells you the rate your equipment gives.

Is the printed flow rate what I get?

Usually less. Filter media, hoses and height reduce flow, so the real turnover is lower.

How do I find my tank's volume?

Use the Aquarium Volume Calculator.

Is higher turnover better?

Not always. Some fish dislike strong currents. Follow advice for your species.

Does the filter's rating match real flow?

Real flow is lower once media, hoses and height are included, so treat the rating as an upper limit.

Can I enter gallons per hour?

Yes. Switch the unit toggle to imperial.

Reviewed by a licensed veterinarian
Last reviewed 18 Oct 2026 · How we review

Sources

  1. Pure arithmetic / unit conversion on user inputs (no external constant)
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Estimates only. Every pet is different — confirm with your veterinarian.