How to Size a Fountain Pump
Selecting a pump for your pond or fountain involves more than just choosing a particular style or design. Submersible fountain pumps come in many sizes and you should choose them based on how much water your water feature holds and lifts within a given period. Most small fountains and ponds require the simplest submersible pump, designed to re-circulate 50 gallons or less an hour. Larger ponds with fountains or waterfalls necessitate a more robust pump. The most important element in sizing a fountain pump is determining the maximum head height rating and maximum lift.
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Measure the diameter of the fountain spout with a tape measure. You will be calculating the gallons per hour, or GPH, by multiplying the diameter by 100. For example, if your fountain spout is 1 inch in diameter: 1 x 100 = 100 GPH, your pump will need to be rated at 100 GPH.
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Measure the entire height of the fountain from the pump to the fountain head or spout. This measurement determines the maximum head height rating, which is how high the pump will need to lift or push the water to reach the fountain head. This measurement is different from the “pumping height” which is the measurement from the outlet port on the pump to the top of the water.
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Look at the pump package for fountain specifications. For example, you might see the following specifications on a fountain pump package: Pump type, submersible; GPH, 170.0; maximum lift (inches), 49.0; horsepower (HP), 0.01; UL, CSA Safety Listing, Yes; warranty, 2 years.
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Choose a pump that is at least one and one-half times the head height for optimal performance. For example, if your fountain is 30 inches tall, find a pump with a maximum lift of 45 inches or more. Choosing a pump with a maximum head height that is higher than your fountain ensures a strong water flow into the fountain and out of the fountain head. You can always use a flow reducer to slow the flow, but you would have to purchase a stronger or higher rated pump to increase the flow.
Tip
Always use the correct tubing size as it has a direct effect on the pump's maximum lift capability. Using smaller tubing than specified limits the amount of water circulated and also limits maximum lift.
Warning
Always make sure the submersible pump is unplugged during installation or when making adjustments. Picking up a live pump with wet hands or when standing in water or on wet surfaces can cause a fatal electrical shock.
References
Writer Bio
Based in Atlanta, Valerie Liles has been writing about landscape and garden design since 1980. As a registered respiratory therapist, she also has experience in family health, nutrition and pediatric and adult asthma managment. Liles holds a Bachelor of Arts in journalism from Colorado State University and a Master of Science in technical communication from the University of Colorado.