How to Calculate Pond-Pump Size
- 1). Determine the volume of water in your rectangle pond by calculating length in feet by width in feet by depth in feet. For a circular pond, calculate 3.14 by 1/2 diameter in feet by 1/2 diameter in feet by depth in feet. Multiply the volume by 7.5. This tells you how many gallons of water are in your pond.
- 2). Measure the length of the spillway for any waterfalls or streams. Multiply this number by 150 GPH.
- 3). Add the volume of water to the number you got in Step 2. This tells you the minimum GPH your pump needs to handle. Purchase a pump that handles at least that amount. However, buying a pump slightly stronger than your estimated need is recommended.
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