Liner Size

Length of liner = (Maximum Pond Length) + (2 x Depth)
Width of liner = (Maximum Pond Width) + (2 x Depth)

Example:
Pond Size: 11ft x 16ft Pond, 2ft deep

Length = 16ft + (2x2ft)
Length = 16ft + 4ft
Length = 20ft

Width = 11ft + (2x2ft)
Width = 11ft + 4ft
Width = 15ft 15ft x 20ft liner required for a 11ft x 16ft, 2ft deep pond

Gallons of Water in the Pond

Total Gallons in the Pond = Average width (ft.) x average length (ft.) x average depth (ft.) x 7.48
(7.48 gallons in a cubic foot of water)

Example:
Pond Size: 11ft x 16ft, 2ft deep

Total Cubic Feet = 11ft x 16ft x 2ft
Total Cubic Feet = 352ft 3
Total Gallons in the Pond = 352ft 3 x 7.48
Total Gallons in the Pond = 2633

2633 Gallons of water in a 11ft x 16ft, 2ft deep pond

Gallons of Water in the Stream

Total Gallons in the Stream = Width x Length x .25 x 7.48
(7.48 gallons in a cubic foot of water)

Example:
Stream Size: 4ft x 20ft

Total Gallons in the Stream = 4ft x 20ft x .25 x 7.48
Total Gallons in the Stream = 150
150 Gallons of water in a 4ft x 20ft stream

Correct Size Pump

This is the most tricky calculation because the flow rating of a pump does not mean you will get that amount of water.

When determining the correct size pump, there is a few things you must take into account... To properly maintain the pond balance you will need to turn over (recirculate) the entire body of water every 1-2 hours. For very large ponds you may need more than one pump/waterfall. To create a nice waterfall that does not look like a small trickle you will want to deliver at least 1500gph of water per foot of width of waterfall. That means... A small 6" wide waterfall will require 750gph of water whereas a 2ft wide waterfall will need at least 3000gph.

As mentioned earlier, the flow rating of a pump does not mean you will get that amount of water. Look at the example below to see how to determine what pump is right for you.

Example:
Pond Specs: 16ft x 16ft, 2ft deep.
2ft wide water fall.
70ft stream, 80ft hose length (between pump and fall)
2" hose diameter
Waterfall 10ft higher than pond water level. (Elevation)

Using the calculation shown in a previous section, we see that this example pond has 3830 gallons of water in the pond and 262 gallons of water in the stream, for a total of 4092 gallons of water. To turn the entire body of water over in 1-2 hours a 2000gph to 4000gph pump will be required. The waterfall is 2ft wide; therefore, it will need at least a 3000gph pump.

After taking the specs into account, let us assume a 3000gph pump will do... To verify that it will be ok, we put the information into the calculator below. We get a TDH result of just under 14ft. TDH means Total Dynamic Head... have I lost you yet? It is just a fancy formula to calculate the resistance caused by such things as pumping distance, pumping height, different types of pipe, pipe diameters, etc. In other words, it is the resistance value of all the factors added together.

Now we take that value and look at the pump chart provided by the pump supplier to see how it preforms at that TDH. Our high end 3000gph pump will produce approx. 1400gph-1500gph with a TDH of 14ft (See chart below). That is not enough to meet either of our 2 requirements; therefore, a larger pump will be required.