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Thread: How long to wait between ph tests when adding borax

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    How long to wait between ph tests when adding borax

    Hello. First, let me thank this forum for helping me successfully manage my first summer of pool ownership. I have learned so much through reading the Pool School and hundreds of posts that have been made on a wide variety of subjects!

    I am attempting to help a friend SLAM her pool to get rid of an algae attack, and we need to bring her ph level up first.

    How long after we add the borax can we accurately re-test the ph levels again? I think I read somewhere on here ~2 hours, but I can't seem to find that piece of information now...

    Thanks so much!
    24x4 round AG Doughboy, 13.5K gallons, installed 2007
    Multiport Sand filter, Hayward Power Flo LX pump, HP: 1.5, SPL: 70 GPM
    Manual vacuum, nylon brush, Auqaluminator light, wedding cake stairs

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    linen's Avatar
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    Re: How long to wait between ph tests when adding borax

    Welcome to tfp, Runningfan

    We generally recommend waiting an hour between chemical additions before testing again and redosing.

    What is her ph now? What is her TA now? What is her cya now?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Patrick_B's Avatar
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    Re: How long to wait between ph tests when adding borax

    Welcome to the forum!
    TFP Moderator
    Essential Links:
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    28K Gal IG FreeForm, CLI Quartz, Pentair 36"SF & VS Pump, Dolphin M5, Rheem

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    Re: How long to wait between ph tests when adding borax

    Thanks, all!

    FC = 22
    CC = 1
    TC = 23
    pH = 6.8
    TA = 100
    CYA = 100+
    CH = 320

    Using the tablet chlorine, so that is why CYA is so high and pH is so low...
    24x4 round AG Doughboy, 13.5K gallons, installed 2007
    Multiport Sand filter, Hayward Power Flo LX pump, HP: 1.5, SPL: 70 GPM
    Manual vacuum, nylon brush, Auqaluminator light, wedding cake stairs

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    Re: How long to wait between ph tests when adding borax

    And she is borrowing my TF100 test kit.
    24x4 round AG Doughboy, 13.5K gallons, installed 2007
    Multiport Sand filter, Hayward Power Flo LX pump, HP: 1.5, SPL: 70 GPM
    Manual vacuum, nylon brush, Auqaluminator light, wedding cake stairs

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    Re: How long to wait between ph tests when adding borax

    He aware ph test isn't accurate above FC of 10
    18x36 inground vinyl lined, Hayward sand filter and tablet chrolinator, approx 18k gallon

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    Re: How long to wait between ph tests when adding borax

    This pool needs some work before SLAMming it. The pH should have been raised before adding the chlorine because the pH will read higher than what it is when the FC is above 10. Trying to SLAM a pool with the CYA 100+ is going to be a tough process.

    Test the CYA level again by using half pool water and half tap water. The test result will then be about 1/2 of the CYA level. So if the test reads 70, then the CYA level would be 140. Doing the CYA test this way will let give you a better idea of how much water will need to be drained.

    You should drain some water off to lower the CYA level to 50 before SLAMming as this will make the process much easier to complete.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: How long to wait between ph tests when adding borax

    Thanks for the help!

    Yes, my understanding is that the pH test tends to read low when the FC is over 10, so we suspect it may be even lower than 6.8. So it definitely is what we're trying to fix first.

    We also know the CYA is really high and will need to come down, but refilling the pool is very costly here, and she had planned on closing this weekend anyway. It will be cheaper in this instance to just raise the chlorine levels up (WAY up) to kill the algae before she closes. Then next summer, she will drain and refill and bring down the CYA and start the season out on the right foot.

    Ping, thanks so much for the tip on the 1/2 and 1/2 CYA test. All we know right now is that it's over 100...that's as high as the test goes. So that will be helpful in getting a more accurate read.
    24x4 round AG Doughboy, 13.5K gallons, installed 2007
    Multiport Sand filter, Hayward Power Flo LX pump, HP: 1.5, SPL: 70 GPM
    Manual vacuum, nylon brush, Auqaluminator light, wedding cake stairs

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    Mod Squad Bama Rambler's Avatar
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    Re: How long to wait between ph tests when adding borax

    I think that the pH actually reads higher than real when the FC is high.
    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
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    Re: How long to wait between ph tests when adding borax

    Yes it does. It may be a good idea to up the ph in this case during slam if closing. Don't want acidic water sitting closed. Or let FC drop below 10, get accurate test and adjust properly.
    18x36 inground vinyl lined, Hayward sand filter and tablet chrolinator, approx 18k gallon

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    Re: How long to wait between ph tests when adding borax

    Yes. False high pH with the phenol red pH/color block test and >10 FC.
    TFP Moderator
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    Re: How long to wait between ph tests when adding borax

    Let the FC drop below 10 and adjust the pH to 7.5 then close the pool. I would not bother trying to clear it up since it is going to be closed so soon.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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