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Thread: Why is my PH Dropping?

  1. Back To Top    #1

    Join Date
    Jul 2009
    Location
    Long Island, NY
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    262

    Why is my PH Dropping?

    I have a SWG but my PH is dropping. My current TF100 test results are:

    PH = 7.2
    FC = 13
    CC = 0
    TC =13
    Borates = 50 (approx.)
    TA = 70
    CYA = 80
    CH = 50
    Temp = 85

    So far this season, I have added 6 pounds of 20 Mule Team Borax to raise the PH. I have recently added CYA to bring it up to my target of 80. It has only been a couple of days since I added the CYA so I am still trying to dial-in on the correct setting for my SWG. That's why the FC is presently on the high side. I want to target a FC of 8 or 9.

    I have read the extended test kit directions for the PH test and understand that the reagent is compensated up to a FC level of 10. When FC level is between 10 and 20, the test result is higher than actual. So, if I understand this correctly, I may have a PH of less than the 7.2 reading that I got today.

    Since SWG's tend to cause PH to rise over time, I'm not sure why mine is dropping. The only thing different this year is that I am using a solar blanket. Could this have an effect of the PH? Also, since my borate level is already around 50, should I still use more borax to raise the PH?
    Free-form concrete walls with vinyl liner, 18,000 gallon capacity, Jandy 1.5HP e-Pump, Jandy DEV48 DE filter (using cellulose media), Jandy AE2500 heat pump, Jandy Aqualink Power Center with 14-blade cell kit and Jandy PDA-P8 wireless control system.

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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: Why is my PH Dropping?

    Continuing to use borax to raise the PH is fine.

    The solar blanket will stop CO2 outgassing, thus preventing the usual PH rise. Also, your TA isn't all that high, so I wouldn't expect all that much PH increase, though seeing a little would be normal without a solar cover.

    Remember that adding CYA will bring down 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

  3. Back To Top    #3

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    Jul 2009
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    Re: Why is my PH Dropping?

    I didn't realize the effect of adding CYA on PH. I went back to the Pool Calculator and found that adding 50 oz of stabilizer will drop the PH by 0.39 which is pretty much what happened. Thanks again for the help.
    Free-form concrete walls with vinyl liner, 18,000 gallon capacity, Jandy 1.5HP e-Pump, Jandy DEV48 DE filter (using cellulose media), Jandy AE2500 heat pump, Jandy Aqualink Power Center with 14-blade cell kit and Jandy PDA-P8 wireless control system.

  4. Back To Top    #4

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    Jul 2009
    Location
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    Re: Why is my PH Dropping?

    Follow-up question - Should I even bother with adding borax now or just let the PH rise on its own over time?
    Free-form concrete walls with vinyl liner, 18,000 gallon capacity, Jandy 1.5HP e-Pump, Jandy DEV48 DE filter (using cellulose media), Jandy AE2500 heat pump, Jandy Aqualink Power Center with 14-blade cell kit and Jandy PDA-P8 wireless control system.

  5. Back To Top    #5
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Why is my PH Dropping?

    As long as your PH is at least 7.2, you can just leave it alone and it will most likely come up on it's own over time.
    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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