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Thread: Ph unstable

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    Ph unstable

    Let me first say, I am new to pool ownership. We have owned our house since June that had a pool built in 2008. Since living here, the pool has been crystal clear and all I have done is added salt (based on salt cell reading which I have now figured out is incorrect and I added too much salt). About a month ago, I started noticing white flakes which I now know is calcium. Our tap water is high in calcium, so when I top it off, it won't lower the calcium . I took my water in to have it tested and here were the results :

    FC 4
    TC 4
    Salt 4,500
    CYA 20
    TA 80
    pH 8.0
    Phosphates 500
    CH 650

    I used Alkalinity up to increase the TA before adding acid. I then added 32 ounces of MA. I then added water conditioner to increase the CYA.

    My numbers as of today are:

    TA 120
    pH 8.2
    CYA 60

    Since having the water tested a week ago, I have added a GALLON of MA and I still can't get the pH to stay in the range. Yesterday, it was 7.4 and today 8.2?? I am so frustrated!! Ant idea why I can't get the pH to stay in range?
    10,000 gallon inground saltwater pool painted bottom
    Aqua rite goldline generator
    Hayward T-Cell-15
    Hayward swimclear cartridge filter

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    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: Ph unstable

    Welcome to TFP!

    The pH is rising because the TA is too high and you are using a saltwater chlorine generator. You should have been adding acid to keep the pH in check. Not testing and maintaining the pool for years was risky.

    The flakes are calcium carbonate being formed in the saltwater chlorine generator cell because your water is out of balance and over-saturated with calcium carbonate. Assuming 85F water temperature, the Calcite Saturation Index you can calculate in The Pool Calculator was (before you added Alkalinity Up) +0.56 and now after adding the Alkalinity Up it is +0.89. This assumes the pool store tests are accurate, which is doubtful. Adding Alkalinity Up was the wrong thing to do -- your TA was fine where it was and could even have been lowered more given the tendency of the pH to rise and the already high CH.

    Start reading the Pool School. In particular, you want to look at Water Balance for SWGs and how to Lower Total Alkalinity.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Ph unstable

    I have only owned the pool for 3 months, it was built by the previous owner. So it wasn't neglected for that long. And I actually had a pool guy initially that had been adding acid, but I fired him and am now on my own. I assumed the pool store knew what they were talking about, but clearly they were just trying to sell products!!

    So at this point, I just need to continue to add acid to bring both the TA and pH down?
    10,000 gallon inground saltwater pool painted bottom
    Aqua rite goldline generator
    Hayward T-Cell-15
    Hayward swimclear cartridge filter

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    Melt In The Sun's Avatar
    Join Date
    Oct 2009
    Location
    Tucson, AZ
    Posts
    3,899

    Re: Ph unstable

    That's correct...just keep adding acid to bring the pH into the acceptable range, and the TA will gradually come down along with it.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
    Make each day your masterpiece. - John Wooden

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    Re: Ph unstable

    I had it in acceptable range yesterday...7.4. How does ut jump so much overnight? Could this indicate a bigger problem? I am going to start going through the pool school tonight.
    10,000 gallon inground saltwater pool painted bottom
    Aqua rite goldline generator
    Hayward T-Cell-15
    Hayward swimclear cartridge filter

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    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,084

    Re: Ph unstable

    How does ut jump so much overnight?
    It doesn't. You have a testing error somewhere. I wouldn't bother trying to reconstruct what happened but go forward and see if your tests don't even out.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: Ph unstable

    See Test Kits Compared in the Pool School and get one of these recommended test kits (the TF-100 is the better value).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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