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Pumps Principles for Your Koi Pond

Reprinted with permission of the author
Rod Talley, Performance Pro Mfg.


Performance Pro Artesian

There are many good ways to plumb a pond. These hints are offered, first, as tried and true - but not necessarily the only methods. Secondarily, I hope to give the reader some sense of the principles behind lowest cost, most reliable pond recirculation and water service. Several thoughts should be kept in mind as we begin our subject:

First, a koi pond should not be plumbed like a swimming pool. A swimming pool uses a low volume, high pressure water system: Small pipes. Big pumps. Your pond should be low pressure, high volume, use pipe with an inside diameter of at least 2" going to the pump, and 1 1/2" to 2" or even greater diameter leaving the pump.

Low pressure, high volume is better achieved with a smaller pump than with the ones normally associated with swimming pools and spas. Realize, too, that the pump should run 24 hours a day. For most applications, if your pump requirement is greater than one-quarter horsepower, you probably have a plumbing or filter problem which should be rectified. In addition, the right pump, properly plumbed, can save 50 percent or more per month in electricity over the wrong one:

  1. Locate the pump as close to the source as possible. It is best to have your main run of pipe on the discharge side of the pump.

    Install the pump outside the pond, and below the level of the surface of the pond to create flooded suction. This will help to ensure a proper supply of water to the pump. Remember, a pump can't pump out water if there isn't any available. Even if your supply line comes up and over the top of the pond wall, it will still offer a flooded suction if it has no breaks to atmosphere before it goes back down below the surface level.

  2. If it is not possible to provide a flooded suction installation then: position the pump as low as possible, and as near the source as possible.

    Install a priming pot on the inlet of the pump.

    Install a foot valve, or a check valve in the inlet line below the water level.

    Always prime the entire inlet line, priming pot, and pump before turning it on.

  3. Always have your inlet pipe diameter equal to or larger than the discharge line.
  4. Use large enough pipe to minimize friction loss. You receive no benefit from fighting friction. It is much better to spend a little more money on the pipe initially, than to continually spend more money on electricity to produce pressure to fight friction. We suggest keeping your friction losses to less than 10 feet per 100 feet of pipe. It costs money to create pressure. The longer the run of pipe you use, the more critical this is. To determine your losses to friction, determine your flow rate and consult a friction loss chart. The inlet and discharge port sizes of the pump do not dictate the proper pipe diameter to use. Normally a minimum of two inch line on the inlet side of the pump and one and a half inch line on its discharge side is suggested for flow rates of up to 50 gallons/minute.
  5. Use a filtration system that does not require a lot of pressure. It costs money to create pressure. Biological filters work best anyway.
  6. Never allow a horizontal centrifugal pump and motor unit to become submerged. If this ever accidentally occurs, shut the unit down, disconnect it, and have a reputable service shop examine the motor.
  7. Never run a pump dry. This will damage the seal and impeller. They are designed to pump fluid, not air. Ensure the pump is full of water before you turn it on, and that it doesn't outpump the supply.
  8. Shelter the pump and motor unit. They will last much longer when protected from rain and rust. The covering should still allow the unit to have suitable air circulation for proper cooling.
  9. If more flow than a single unit can produce is required, use two or more units in parallel. This also offers the benefits of being able to vary the flow rates, ensure partial flow if one unit needs servicing, and can often save a substantial amount of electricity compared to using one very large pump.
  10. Choose a pump that can give you the required flows at the lowest possible amp draw, and its effect on your monthly utility bill can be significant.
  11. If you want to reduce the flow rate of the pump, you can partially close a valve on the discharge side of the pump only.
  12. Check to be sure the motor's electrical connections are set up to match the supply voltage.
  13. Install shutoff valves before and after the pump, so you can easily remove it from the line without having to drain your system.
  14. Use teflon paste (not tape) for sealing threaded joints.

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