How Do I Calculate Swimming Pool Flow Rate?

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Things You'll Need

  • Tape measure

  • Calculator

Calculate the rate of flow of water for a swimming pool to size the pool's pump properly.

The rate of flow of water in a pool is an essential calculation for a pool owner when it comes to purchasing or replacing pool equipment. The flow rate will determine the turnover rate, which is the amount of time it takes the pump and filter to circulate the volume of water in the pool. Water clarity is at its peak when the turnover rate of the pool is between six and eight hours. To calculate the rate of flow for your swimming pool requires some basic calculations.


Step 1

Measure the pool to find the length, width and depth of a rectangular pool or the depth and radius of a round pool.

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Step 2

Multiply the length times the width times the height for a rectangular pool or multiply the depth times using pi (3.14) times the radius, times the radius to find the volume in cubic feet.


Step 3

Multiply the value in cubic feet by 7.48, which is the gallons of water per cubic foot of water. This is the total gallons of water in the pool.

Step 4

Divide the total gallons of water in the pool by the turnover rate in hours. Ideal turnover rate is between six and eight hours. To run the pump less time each day, lower the turnover rate. This will give you the gallons per hour or GPH.

Step 5

Divide the gallons per hour by 60 to find the gallons per minute, or GPM.


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