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  1. #1

    Priming an external pump


    I am going to install an external pump to a retro bottom drain.

    I will have a non return valve in the pond.

    It seems a "prime pot" would be needed just in front on the pump so it can be primed anytime work is done on it etc.

    Something like this:


    However, i am wondering if i can just use a tee in line (has to be right height too) with a the middle tee pointing vertically and a screw end cap.

    I could unscrew it, top up water and screw tight to ensure water end to end, pond to pump.

    Anything i am missing??

    Thanks Karl

  2. #2
    The correct way to use a strainer basket pot to prime a pump is:

    • Close a valve immediately on front of it
    • Unscrew the lid
    • Fill the pot with water
    • Put the lid back on
    • Turn on the pump
    • Open the valve

    Note; Opening the valve is the last operation and should be done immediately after turning on the pump and you don't need the tee arrangement.

  3. #3
    Thanks very much Manky

    Couple of questions:

    1) do you think a simple tee with a screw cap/bung could replace the strainer pot? Or is it missing something - e.g. Too little volume/not enough seal or such?

    2) if you have a non return valve on the pond side...do you still need this extra valve? Can you explain that a bit?

    Thanks karl

  4. #4
    The strainer pot has a much larger volume in order to ensure that there is sufficient water available at the pump suction for it to always successfully prime up even if the pipework leading to it has drained. You will get a good seal with the tee arrangement but two disadvantages spring to mind.

    The first is that, in the tee arrangement, there will be much less water so the pump may not always prime. The second is that, unless there is a place for air to escape when you fill the tee, you may cause an airlock in the pump or the inlet pipework and the amount of water available to the pump will be even less. By using a strainer pot, you solve both problems.

    When you plumb in a strainer pot, it should be arranged that they are at the same level i.e. the water level when it's being filled should be such that the water will also flow into the pump rather than the pump having to "suck water up hilI" from the pot through empty pipework. It's also good practise that the pump and strainer shouldn't be any further above the pond water level than necessary.

    I prefer not to use non return valves because they are a small restriction to flow and they are prone to forming a biofilm which can prevent them from sealing effectively. Is the pond in-ground or above ground?

  5. #5
    Member Rank = Tosai carpingsparky's Avatar
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    Nov 2020
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    Hi Karl, i have a retro bottom drain piped over the pond wall to a ball valve to a standard varipump through a non return valve to my filter system. Once its up & running you will never have to prime the pump because the pump if its below the pond level & install a non return valve. Hope this helps Martin.

  6. #6
    Extreme Koi Member Rank = Sansai StevePeps's Avatar
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    Aug 2014
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    Silly question

    I have a 20000 varipump and retro drain

    anyone got any photos how to set them up , have tried with my submersible pump but never worked .

    question is what do you mean ‘prime it’ , pump is new in box


  7. #7
    Hi Steve

    I will leave more experienced people to give you the fuller answer...but priming is making sure the pump is full of and fed water straight away on start up. These things can't start dry/with empty pipes...they need water immediately. Various ways to achieve that...have it gravity fed, have a prime pot...

    If you just plumbed a pump in dry and hoped it sucked the air out the pipe until the water.reached it...then it would probably blow the pump.

  8. #8
    Extreme Koi Member Rank = Sansai StevePeps's Avatar
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    Aug 2014
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    Thanks JustK

    Pond is pump fed , pump will be above water level .


  9. #9
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    Mar 2018
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    I had one mate. My whole life is a bodge mind lol but I just to switch pump off close pump out by any means hand over out of no valve or wjat ever. I did have the pot so filled with a bucket then sucked thought pipe to syphon then quickly stick pipe on pump switch on and tighten any clips was a right bugger like

    Sent from my F5121 using Tapatalk

  10. #10
    Junior Member Rank = Tosai Tinca's Avatar
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    Jun 2019
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    Another bodge artist .
    To prime my system i stuck a sump pump in the pond and a pipe on my inlet feed started the sump pump then started main pump.
    As long as i shut return valve first seconds before turning off pump i dont need to re prime



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