The most important information you should know about your pond is the number of gallons of water it holds. Your pump size and water treatments are based on this number. You can use the following calculations to determine how much water is in your pond.
There are 7.48 gallons of water per cubic foot.
To figure gallons in your pond: (All measurements are in feet)
Rectangular pond: Length x Width x Depth x 7.48 = Gallons in your Pond
Round Pond: 3.14 x r2 x Depth x 7.48 = Gallons in your Pond
r2 = Radius x Radius (Half pond diameter times itself)
Natural Ponds: Length x Width x .8 x Depth x 7.5 = Gallons (.8 compensates for lack of corners. Use .85 for ponds 400 plus square feet)