How to Determine the Pump Size for a Fountain
- 1). Determine the number of gallons of water in the pond. This will help determine the size of pump you need.
- 2). Calculate the number of gallons of water in a rectangular pond by multiplying the length times width times depth by 7.5. Configure the number of gallons of an oval pond by multiplying the length times width times depth by 6.7. For a circular pond, multiply the diameter times the diameter times by the depth times 5.9.
- 3). Select the correct pump by choosing a pump that will move at least half the gallons of water every hour. For example a 300-gallon pond would need a pump that circulates 150 gallons of water per hour.
Source...