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Thread: Is this possible?

  1. Back To Top    #1

    Join Date
    Sep 2010
    Location
    Tampa, FL
    Posts
    14

    Is this possible?

    Just got done shocking my pool for about 3 days. I hadn't tested PH during this time because I read on this site that PH test is unreliable at high chlorine levels. With CYA=60, I was shocking in the FC=high 20s.

    FC is now down to 10.5ppm and I tested PH expecting it to be high since I shocked with liquid chlorine.

    However, PH has gone from 7.6 down to 7.0-7.2 during shocking.

    Is this possible? I've run the test several times to be sure.

    To summarize

    FC=10.5
    CC=.5
    TC=11.0
    CYA=60
    TA=70
    PH=7.2
    CH=250

    According to pool calculator, about 3lbs of Borax should do it, but I was expecting to have to add acid.

    I did use a little chlorine neutralizer to get FC down before a play date. Not sure if that could drop the PH.

    Thanks

    Doji
    15,000 gallon outdoor in-ground plaster pool
    Sand filter flow rate 62 GPM
    3/4hp pump

  2. Back To Top    #2

    Re: Is this possible?

    What did you use to shock?

  3. Back To Top    #3

    Join Date
    Sep 2010
    Location
    Tampa, FL
    Posts
    14

    Re: Is this possible?

    Quote Originally Posted by dojiboy
    since I shocked with liquid chlorine.
    15,000 gallon outdoor in-ground plaster pool
    Sand filter flow rate 62 GPM
    3/4hp pump

  4. Back To Top    #4
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Is this possible?

    Possible: certainly, even though it is not what I would expect.

    There are a couple of different kinds of chlorine neutralizers. Most of them are more or less PH neutral, but some lower the PH.
    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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