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Thread: pump will not hold prime when turned off

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    Join Date
    Jul 2010
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    Edmond, Ok
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    pump will not hold prime when turned off

    Hello, I am new to the forum and was hoping I could get some help with my problem. I have an IG pool, 29K gallons, cement, 2 skimmers 1 MD, Sand filter, 1hp pump. SWG.

    I am losing prime when I shut the pump off. Also, I have bubbles enter the pool through the 3 jets closest to the equip. when pump is running. Here is what I have done so far. After turning off pump I closed all three jandy valves on the the MD and 2 Skimmers. Still loses prime. I can see bubbles enter the basket through the drain side. I have turned the multi valve to closed with same result. I have run water over all the connections while running with no noticable difference in the sound of the motor or change in the bubbles in the basket. I am trying to determine if the leak is in the suction side or the pressure side. When the pump is running it never completely primes as I always have some bubbles in the basket. It is running at 10 psi.

    Question 1) by closing the jandy valves on the 2 skimmers and the MD and still losing prime does this indicate there is not a leak on the suction side? The valves are located about 6inch from where the pvc comes out of the ground. Provided the jandy valves are working properly.
    Question 2) does bubbles coming out of the jets indicate an air leak on the return side?


    Any help would be greatly appreciated, I have read through some post earlier trying to find a solution first but no luck yet.
    29K gal cement pool, 1.0 HP pump motor, Sand filter, SWCG, Polaris 380 "Oscar" cleaner with booster pump,

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: pump will not hold prime when turned off

    Your symptoms suggest an air leak on the suction side of the plumbing. The valve test you mentioned doesn't prove that there isn't an air leak, it just narrows down the area the leak can be in.

    Try getting a garden hose and running water over different sections of the plumbing while watching the pump strainer basket. If air stops entering the strainer basket, the area the garden hose is running on is the area with the leak.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    duraleigh's Avatar
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    Apr 2007
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    Sebring, Florida
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    Re: pump will not hold prime when turned off

    Hey, mdd,

    Welcome to the forum. Agreeing with Jason, it is surely on the suction side. If you are completely positive the bubbles are coming from the pipe, this wont apply but two common sources of the leak are a bad gasket on the lid to the pump strainer basket or a drain plug that is not sealed in the bottom of the pump strainer basket.

    The presence of bubbles in the returns still points to a suction side leak......the air is simply being forced first into the filter then out to the returns.

    It's almost an ironclad rule that air in the system is a suction side leak and a pressure side leak results in water being spewed from the system.

    Could the leak be within the Jandy valve?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

    Join Date
    Jul 2010
    Location
    Edmond, Ok
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    Re: pump will not hold prime when turned off

    Guys, thanks for the quick replies. I was able to locate the problem by going back over the connections with a water hose again as Jason suggested. I have a water fall that has its own pump and is plumbed into the end of the suction pipes coming out of the ground. There is a pvc shut off valve there that has a bad o-ring at the screw-on union. This has eliminated about 98% of the air in the basket. the pump is on a timer and set to shut off at 8am so I will check to see if it holds prime and for how long tomorow when it shuts off. It did hold its prime for over 30min this evening which was far better than what it had been doing. Thanks again for the help, I have found this forum to be most useful with the posts I have already read! Now on to the problem with the lights!
    29K gal cement pool, 1.0 HP pump motor, Sand filter, SWCG, Polaris 380 "Oscar" cleaner with booster pump,

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