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Thread: Pump runs primed but loses water when off

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    Pump runs primed but loses water when off

    I have a 2hp Jandy thats about 6 yrs old. Just recently it started to lose water only when shut off. I can see and hear the air as it leaks into the pump only when it is shut off. The pump is off about 16hrs at a time and the water level in the basket when it kicks back on is about 3 inches high or so. Again, it primes up and runs just fine, no air bubbles circulating around when running. I replace the entire lid assembly with O ring but that didnt solve the problem. Since the pump is otherwise running as it should, do I need to be that concerned?
    35,000 gal pool
    Pentair whisper flo & Cartridge Filter
    Caretaker 99 in floor
    Suntrek Solar panels
    Las Vegas,NV

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump runs primed but loses water when off

    Yes you need to be a little concerned because it's probably going to get worse and one day may not prime at all.

    Is there any evidence of water leaking around the pump? The shaft seal is a likely suspect but it could be anywhere.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Pump runs primed but loses water when off

    A loose pump plug has potential too.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Pump runs primed but loses water when off

    no water leaking anywhere around the pump or plumbing. no wet spots on cement. drain plugs feels tight. Mabey its a small crack in the housing of the pump but cant see anything obvious, besides if it was a crack , I would think I would see some water droplets seeping out of it somwhere while its running.
    35,000 gal pool
    Pentair whisper flo & Cartridge Filter
    Caretaker 99 in floor
    Suntrek Solar panels
    Las Vegas,NV

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump runs primed but loses water when off

    Does your filter valve have a waste outlet? If so check it for a small leak.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Pump runs primed but loses water when off

    do you mean backwash valve?.. I have a cartridge filter w/no separate backwash plumbing. but to clarify..if it was a suction side leak, wouldn't I see air in the pump basket while it was running? just want to completely rule out that possibility.

    I had a pool guy suggest some sort of small crack in the the pump in the area where the lid attaches to the pump and that the pressure of the suction of the pump on the lid (sucking it down tight when on) is eliminating any visible signs of air intake while its running. but I would think I would see water squirting out when shutting off the pump. didnt notice any before but will check again just to make sure.
    35,000 gal pool
    Pentair whisper flo & Cartridge Filter
    Caretaker 99 in floor
    Suntrek Solar panels
    Las Vegas,NV

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    JasonLion's Avatar
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    Re: Pump runs primed but loses water when off

    Air leaking into the pump only when the pump is off can be caused by a leak in the plumbing anywhere on the filter side of the pump that is above the pool water level. It is also possible for the pump strainer basket lid to cause such a leak as well, though that is relatively rare. If it is on the filter side of the plumbing, it should leak water when the pump is on. The water leak might be quite slow, as even a very small water leak will let in a fair bit of air.
    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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    Re: Pump runs primed but loses water when off

    this is weird...so I checked yesterday morning to see how much air had seeped into the pump basket area overnight and I noticed the water level was higher than it had been but still a significant drop from full. This morning I go out to check and its almost full, just a small air pocket. it hasnt been that full since I started to notice this problem a few weeks ago. go figure?

    Since there's no obvious area of leaking or whatever to pinpoint the mystery air, I'll just keep an eye on it and not really worry about it unless something else happens that may cause not to run fully primed.
    35,000 gal pool
    Pentair whisper flo & Cartridge Filter
    Caretaker 99 in floor
    Suntrek Solar panels
    Las Vegas,NV

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    Re: Pump runs primed but loses water when off

    decided to post the solution to this problem. the air continued to get into the pump after shutting off. It turned out to be a loose/broken fitting of the ozone generator which was fed into the bottom of the pump from the main generator unit.
    35,000 gal pool
    Pentair whisper flo & Cartridge Filter
    Caretaker 99 in floor
    Suntrek Solar panels
    Las Vegas,NV

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