It is important to know the volume of water in your pond or waterfeature for many reasons including properly sizing pumps and calculating application rates.
Here is the formula for calculating the volume, in gallons, of your pond or watergarden: Length X Width X Average Depth in Feet X 7.5 = Gallons
For example, your watergarden is 10’x20′ and has a depth of 3′: 10x20x3x7.5=4,500 gallons.
If your watergarden or pond has different depths use the average depth or section off the waterbody. For example, if your feature is 30’x20′ with 10’x10′ section with 1′ depth and a 20’x10′ section with 3′ depth, calculate the gallons in each section and add together. (10×10’x1x7.5) + (20x10x3x7.5)= 750+4500=5,250 total gallons. If you have a larger body of water with several depths, use the average. For example your 50’x50′ pond has depths of 2′, 4′, 6′, and 8′, the average is 2+4+6+8=20/4=5′ so your volume in gallons would be 50x50x5x7.5=93,750 gallons.