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How to Choose the Correct Size Pond Tubing

How to Choose the Correct Size Pond Tubing

We often get asked – ‘What size pond tubing should I use with my pump?’ Pond tubing is an often overlooked piece of pond equipment, but if you choose tubing that it too small, it will significantly decrease the flow of your pump.

How to Choose the Correct Size Pond Tubing

Pond owners often put a lot of thought into the pump they choose, but usually very little into which size tubing to use. A pump must have the power to not only push water vertically up to the top of the waterfall or filter, but also overcome the friction created inside the tubing or pipe. Choosing the correct diameter of kink free or PVC tubing is crucial in how well your pump will perform.

Size Matters! Pipe Diameter vs Surface Area

Although it doesn’t seem like there is a big difference in size between ¾” and 1” tubing, the 1” tubing has 80% more surface area (the space inside the pipe) than the ¾”. That is a huge difference. The same is true when you compare 1 ½” and 2” tubing. The chart below shows the surface area inside of various sizes of pond tubing. What does this mean? Basically, when you compare 1 ½” and 2″ tubing, it would take 2 separate lines of 1 ½” tubing to provide as much surface area of the 2” tubing.

Pond Pipe Diameter vs. Surface Area

Tubing DiameterSurface Area (square inches)
3/4"0.44
1"0.79
1 1/4"1.23
1 1/2"1.77
2"3.14
3"7.07
4"12.57
6"28.27
8"50.26

Friction Loss

The faster water is pushed through a pipe, the more turbulence and friction is produced. This friction creates more pressure and results in lower flow. This is referred to as Friction Loss. Attaching a small diameter tubing to a large pump drastically increases the friction and restricts the flow. In addition, the longer the length of pipe used, the pronounced the effect is.

Example:

Let’s say you you bought a pump that has a flow of 3300 gallons per hour (GPH). You have a long stream connecting your waterfall to your pond, so you need 50’ of tubing. The pump comes standard with a 1 ½” tubing adapter, but is that really the best tubing to choose?

  • 1 ½” pipe has about 10’ of friction loss in 50’ of tubing when water is pumped through it at approximately 3600 GPH. This is equivalent to forcing the pump to push the water 10’ vertically up.  This puts a lot of extra back-pressure on the pump and it could significantly reduce the actual flow of the pump.
  • On the other hand, 2” pipe has only about 3’ of friction loss in 50’ of tubing when water is pumped through it at 3600 GPH. With only 3’ of friction loss, there is much less back-pressure on the pump so it will produce a much greater flow.

 


Here is an example showing the actual effect of tubing size on a pump.

Let’s say you purchased a Tsurumi 3PL pump. This pump has a maximum output of 3300 GPH. As mentioned in the example above, if you run 50’ of 1 ½” tubing to waterfall, there will be around 10’ of friction loss in the pipe (equivalent to 10’ of head pressure). From the chart below, at 10’ of head, the Model 3PL’s output will be reduced to 1800 GPH. But if you use 2” pipe, the friction loss is equivalent to 3′ of head and the pump output will be around 3100 GPH


 

Recommended Tubing Sizes vs Flow Rate

The chart below shows the ideal and maximum recommended flow rates for various tubing sizes. To get the best performance and the most volume of water from your pump choose the ‘Ideal Flow Rate’ column, especially if you are pumping through long runs of pipe (40 feet or more).

DiameterIdeal Flow RateMaximum Flow rate
1/2"300 GPH420 GPH
3/4"600 GPH900 GPH
1"1200 GPH1500 GPH
1 1/4"2100 GPH2700 GPH
1 1/2"3000 GPH3600 GPH
2"4800 GPH5400 GPH
3"12,000 GPH15,000 GPH
4"21,000 GPH24,000 GPH
6"36,000 GPH42,000 GPH

How to Use This Chart

Example:

Assuming your pump output is 3300 GPH and you only need to use 10’ of tubing.

  1. Scroll down the ‘Ideal Flow Rate’ column until you find a number close to 3300 GPH.
  2. You will find 3000 GPH, look to column on the left and it indicates 1 ½” tubing.

 

Although the 3000 GPH in the chart is less than the 3300 GPH of your pump, there will be little reduction in flow if you are using only 10’of tubing. If you needed to use longer runs of tubing, like 50″ in the example above, it is definitely worth while to go to the next larger size of tubing (2″) to get the best performance from your pump.

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