Pond Pump Size Calculations

Figuring out the correct pump size depends upon the how big your pond is. Other factors include whether or not the pump is being used for filtration, recirculation or water features. Another factor is the number of fish and plants your pond contains. Larger fish populations have greater air requirements.

A good rule of thumb is that pumps should be able to pump out about half the pond volume every hour. For example, a pump that moves would be appropriate for a pond.

You don't have to refer to a fountain pump size chart to figure out the best water pumps for your garden. With a few measurements and calculations, you can determine the size pump you'll need.

This is a demo page demonstrating the use of
Physical Quantity and embedding AutoCalcs.

Flow rate for filtration

Filtration flow rate in gallons per hour (gph) = 0.5 x pond volume (gallons)

Flow rate for fountains

For every inch of stream width at the top of the fountain, you need at the height you're pumping

Flow rate for waterfalls

Light flow = x waterfall width (in.)
Average flow = x waterfall width (in.)
Strong flow = x waterfalls width (in.)

Pond volume

Pond volume (gallons) = 7.5 x average width (ft.) x average length (ft.) x average depth (ft.)