How to determine what pump size is suitable for your pool

The chart below shows the performce curve of the Pentair WhisperFlo Energy Efficient swimming pool and spa pumps. Looking at this chart you can see the scale on the left marked "METERS OF WATER" AND FEET OF WATER" which is the total daynamic head in feet/meters of water (TDH) . The total daynamic head in feet of water is the amount of pressure resistance in the pool piping (pipe size, 90 degree turns ...) the pump has to overcome to push water through the pipe. The easiest way to calculate the TDH in a pool is to read the pressure guage (PSI) readings in a cleaned and running pool filter and multiply the PSI by 2.31.

TDH = (PSI x 2.31)

You can also add a constant factor of 10 to compensate for friction loss with piping, filter media e.t.c

Determine the Desired Flow Rate (DFR) in Gallons Per Minute (GPM) for your pool

Example: Desired Flow Rate DFR = 20,000 gallons / 8 hrs x 60 = 41.67 gallons per minute (residential pool)

Now you can read the pump performance curve by following the TDH line across the chart until it crosses your GPM reading. This will give you an idea if you're operating with a proper pump size.

For example, if your TDH reading is 60 and your GPM reading is 100 you should be running a 1.5 HP pool pump as in the Pentair Pentair WhisperFlo

The flow rate in GPM of your pool is determined by the pipe size, and this in turn determines what pump size is suitable for your pool. The table below shows the minimum and maximum flow rates for different sizes of Plastic (PVC) schedule 40 pipe and Copper Type K pipe. The GPM rating of your pump should not exceed the max (gpm) value of the suction line

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