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Thread: Low pressure when vacuum is connected

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    Low pressure when vacuum is connected

    Hi All,

    An odd development this spring:

    When I attach the vacuum hose to the skimmer port, my pump loses pressure pretty dramatically, and the pump basket becomes quite aerated.

    I do connect the vacuum correctly (to where the hose is completely filled with water when I connect it).
    When the hose is not connect, the pump runs well--there is not a bit of aeration in the pump basket.
    The vacuum does continue to work, but not well.

    I will note that my filter does only show about 11 lbs of pressure when running normally, but this was the same as last year, and I did not have any vacuum troubles then.

    Any ideas? Surely it cannot be a leak in the vacuum equipment, as everything is fully submerged anyway. I'm scratching my head here...
    11,500 gal. rectangular cement, 11 x 28 (built c1930); Hayward S180T sand filter; Hayward Max-Flo II 3/4 HP 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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    37,879

    Re: Low pressure when vacuum is connected

    That sounds like there must be an air leak somewhere. Usually there is an air leak in the vacuum hose, often right near where it connects to the skimmer. It is also possible that there is an air leak near the pump that only draws air when the suction from the pump is higher, as it would be when the hose is connected.

    Are you sure that the air shows up in the pump strainer basket even when the entire length of the vacuum hose is under water, including the entire connection to the skimmer? Often, though not always, there is a small portion of the hose above water right at the skimmer.
    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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    Join Date
    Mar 2007
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    Coastalish 'down easter'
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    Re: Low pressure when vacuum is connected

    I agree with Jason that it's probably an air leak, please double check the things he mentioned.

    If you still find no evidence of an air leak, let us know and we'll talk about obstructions and cavitation.
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  4. Back To Top    #4

    Re: Low pressure when vacuum is connected

    Thanks to both of you; I'll try to check on things tomorrow after work, looking to be sure the entire hose is beneath water. I do try to make sure I keep it under water when I pass it through the skimmer door, but I'll give that another go.

    Thanks again!
    11,500 gal. rectangular cement, 11 x 28 (built c1930); Hayward S180T sand filter; Hayward Max-Flo II 3/4 HP pump

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