know your volume

The most important numbers to know in the water gardening world are tied to volume. Volume of your pond, volume capacity of your pump, volume requirements for fish and water treatments; you get the idea. Calculate your volume below!


Calculate your pond or future pond’s volume using the formulas below to help choose the right liner and pump. For more information on pond size and fish care, click here. 

  • For circular ponds, measure in feet the Diameter x Diameter x Depth x 5.9 = Total Gallons 
  • For rectangular ponds, measure in feet the Length x Width x Depth x 7.5 = Total Gallons 

TIP! For Koi fish, there should be 5 gallons of water for every 1 in. of fish. Koi fish have a faster growth rate, so you may have to remove a few of them at a certain point. 

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Choose a waterfall pump to match the height and width of your waterfall. The rule of thumb is for every 1 in. of spillway width, you need 100 gallons per hour flow to achieve a “sheet” look.  

  • Divide by two for a “trickle” look.   
  • Multiply by two for a “Niagara” look. 
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Not all fountain pumps with the same GPH will pump to the same height; generally, a higher GPH will produce a stronger flow. All smartpond Fountain Pumps have flow control to adjust the flow appropriate for the fountain.  

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How to measure your fountain. Measure the distance between the water line and where the water exits. An illustration of the intersection of a three tiered gray concrete fountain. We can see water in each tier basin, and water spraying out of the top.

How to measure fountain pumping height:

  • Measure from the water level to the highest point that the water reaches to find the Ideal Pumping Height. 
  • Choose a pump that has an ideal pumping height greater than the height measured. You can reduce the flow if necessary.

Liner Size

Liners contain all of your pond's water, so it is important to know the size of your liner and the volume of your pond.

LENGTH + (DEPTH X 2) + (2 FEET of overlap) = LINER LENGTH

WIDTH + (DEPTH X 2) + (2 FEET of overlap) = LINER WIDTH

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