Pond Calculations

Use these calculators to quickly plan a pond:

Pump Selector (LINK)
Pond Calculators (LINK)

Calculate liner size

Measure the maximum length and the maximum width of the pond. Add the maximum depth x 2 to each dimension, and then add another two feet of liner to each dimension for your anchor trench.

Calculate approximately how many gallons of water are in a pond

Average length x Average width x Average depth x 7.48 = Total gallons.

Calculate approximately how many gallons of water are in the stream

Maximum length x Average width x 0.25 x 7.48 = Total gallons.

This would be water in transition. Water that has to be supplied by the lower pond is water in transition. Upper ponds, streams, or multiple streams all contribute to this total number.

Calculate approximately how many gallons of water are required to overflow an upper pond

Maximum length x Maximum width x 0.8 x 0.25 x 7.48 = Total gallons required to overflow upper pond.

This would be water in transition.

Calculate how many gallons of water are available to put in transition before the water level in the lower pond is drawn down below the skimmer opening

Maximum length x Maximum width x 0.8 (unless your pond is completely square) x 0.33 x 7.48 = Total gallons available at the skimmer faceplate.

It is recommended that no more than half of the volume of water available at the faceplate is put in transition. If power is interrupted, the lower pond will have to receive all the water in transition, or the pond will overflow.

Stream Depth Fractions

.50 = 6″
.41 = 5″
.33 = 4″
.25 = 3″
.16 = 2″

Surface Area Formula

(Length x Width) / 43,560 = Acres

Pump Calculations

Use the pump selector wizard to find the best pump for the job.

Pump Selector (LINK)
Pond Calculators (LINK)

Calculate how much it will cost to run the pump

Volts x Amps x 24 (hours of operation) / 1000 x .1 = Cost for a 24-hour period.
Amps x Volts = Watts

Just-A-Falls Calculations

Calculate how many gallons of water are in a Just-A-Falls reservoir:

For Reservoir filled with 3″ -6″ sized stone:

Length x Width x Average depth x 7.48 x 0.40 = Total gallons.

60% of the reservoir is mass / rock and 40% is water. This formula assumes 3″ -6″ size stone is used. Smaller stone will decrease the amount of water in a reservoir.

For Reservoir filled with Res-Cubes:

Length x Width x Average depth x 7.48 x 0.85 = Total gallons.

10-15% of the reservoir is mass / rock and 85% – 90% is water.

Calculate how many inches of draw down there will be in a Just-A-Falls reservoir to fill the stream:

Total gallons contained in reservoir / Depth of reservoir in inches = gallons per inch.

Calculate how many gallons of water your stream requires using the stream formula. Try to have three times as much water in your reservoir than you will have in transition.

Total gallons required for the stream / Gallons per inch in reservoir = Total inches the water level will be drawn down in reservoir.

Make sure that there will be enough water remaining in your reservoir to keep the pump completely submersed in water. This is required so that the pump will cool properly.