Aquarium Filter Flow Rate Calculator
Filter flow is often described as turnover: how many times an hour the filter moves the whole tank's water. Enter the tank volume and the turnover you want.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Multiply the tank volume by the number of turnovers per hour to get the water moved each hour.
Filter ratings are often measured with no back pressure. Water in a tank, filter media and hoses slow the real flow, so the rated figure is usually higher than what the filter delivers in the tank.
Worked example
A tank that holds 20 gal with 5 turnovers an hour needs a filter that moves about 100 gal of water each hour.
Questions
What turnover rate is common?
Many guides suggest several turnovers an hour for a freshwater tank. Fish, plants and the type of filter change the right number.
Does a higher turnover always help?
It moves more water through the filter, but strong flow can suit some fish poorly. Watch how your fish use the current.
Why is the rated flow higher than the real flow?
Ratings are often measured with no resistance. The tank, media and hoses reduce what the filter moves in practice.
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