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Thread: Liquidator allowing air in when pump is off

  1. Back To Top    #1

    Join Date
    Jul 2010
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    Pardes Hanna, Israel
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    64

    Liquidator allowing air in when pump is off

    Hi All,

    I have been using the LQ (with the 3/8) for a year now and love it.
    That said, I have been ignoring an issue with it and would appreciate your help fixing it.

    Since my LQ is higher than my IG pool, when the pump turns off water flows slowly from the LQ into the pool (via the outlet), until the OUT float cuts it off.
    The problem, is that despite the check valve on the IN line, water returns to the pool on that line as well.
    Naturally, once the water in the tank reaches the port's level, air gets sucked into the system (which means that my filter always has air in it, and that sucks!)

    I thought maybe the valve was failing but the original 1/4 valve displays the same problem (it was unused before I tested it so there would be no blockage in it).
    The only reason I could come up with for this, is that there is a minimal amount of water (i.e back pressure) that is required for the check valve to work, and that by the time the OUT float cuts of the flow of water out of the LQ, not enough water remains in the tank to allow the IN check valve to work.
    (this also implies that the LQ is not designed to handle my pool setup properly which IMO is not very likely)

    Does this make any sense? Any ideas on how to resolve this?

    A few more things worth mentioning:
    - There are times when it actually works and does not allow backflow (unfortunately, these are the exception)
    - When the flow valve is closed (i.e no OUT flow), the water rises to the maximum in the tank, and no backflow or air returns to the system when the pump shuts off.
    - I can't seem to remember if this has been going on from the moment I installed it, or if it had started later on.

    Yoav.
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Re: Liquidator allowing air in when pump is off

    Replace the check valve with 3/8" SMC model. It seals better and has a low cracking pressure.
    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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    stev32k's Avatar
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    Mar 2009
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    Mobile, Alabama
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    Re: Liquidator allowing air in when pump is off

    Quote Originally Posted by Bama Rambler
    Replace the check valve with 3/8" SMC model. It seals better and has a low cracking pressure.
    Bama:
    Do you have a link for the SMC check valve and needle valve you use. I have a liquidator on the way and would like to get the better valves.
    Thanks
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

  4. Back To Top    #4
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
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    SouthWest Alabama
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    22,333

    Re: Liquidator allowing air in when pump is off

    I got the check valve from US Plastic and the Hayward needle valve from Drillspot. Drillspot may have the check valve too.
    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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