Pipe and Tubing Recommendations for Pumps

A pump's description may provide a discharge size of 1/4", 3/4", or some other size. This does not mean that you should use this size of tubing or pipe for the discharge. Some pumps come with a step down outlet to allow you a choice when selecting the tubing size to connect to the pump. There are several variables for determining the plumbing size for your pond. The " How to Select a Pump" section of the web site will help you when sizing the plumbing for your application.

As a general rule you can use the following pipe sizes for the average pond:

• For pumps with flows up to 300 gph use 1/2" tubing
• Flows from 300 to 600 gph use 3/4" tubing
• Flows from 600 to 900 gph use 1" tubing
• Flows from 900 to 2200 gph use 1 1/4" tubing
• Flows from 2200 to 3500 gph use 1 1/2" flexible PVC pipe
• Flows from 3500 to 5000 gph use 2" flexible PVC pipe
• Flows from 5000 to 12000 gph use 3" flexible PVC pipe

When connecting a submersible pump with a flow rate above 2000 gph you may want to use 1 1/4" tubing to come out of the pond (to allow you to easily pick up the pump for cleaning the inlet) and then connect this tubing to a larger size flexible PVC pipe (which is not quite as flexible as tubing) to gain more flow from the pump. When connecting (for instance) 1 1/4" tubing to 1 ½" flex PVC pipe you will need a 1 1/2" coupling, 1 1/2" x 1 1/4" FPT bushing, and a 1 1/4" male insert.

MNPT means male national pipe thread and is a typical discharge type for a pump. For instance, a pump may have 1/4" MNPT discharge. You can use a 1/4" female pipe coupling to thread onto this or if you are using tubing you can use 1/4" larger tubing to slip over the threads of this fitting for your discharge. Use 1/2" tubing to slip over a 1/4" MNPT fitting or 3/4" tubing to fit over a 1/2" MNPT discharge.

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