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Thread: pH keeps yo-yo'ing up and down

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    Join Date
    May 2014
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    pH keeps yo-yo'ing up and down

    I've been trying to maintain a pH of 7.2-7.5, but it keeps rising and I have been adding 2-3 cups of muriatic acid every other day just to keep it in the range I want. In fact, I got a 7.8 reading today, so I added a good splash of acid.

    I do notice my TA started at 100-110 or so, and when I started adding more acid to keep pH in the low end of the range, the TA came down to 70 (over a few weeks). Should I increase TA to keep the pH stable? I'm hesitant to raise TA because if I do, won't that put upward pressure on the pH - something I don't want at the moment?
    IG gunite pool size: 12,500 gallons - includes spa with spillover, Polaris vacuum cleaner, Ultrapure Ozonator, inline tab chlorinator that I no longer use
    Filter: Hayward Swimclear Model #4030, 4-Cartridge Filters
    Pump: Century, 2 HP with a Hayward 6060 booster pump
    Date of build: March-April 2014 *NEW* : Test kit: TF-100

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    JasonLion's Avatar
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    Re: pH keeps yo-yo'ing up and down

    Why are you trying to keep the PH so low? We recommend keeping PH around 7.5 to 7.8 and towards the high end of that range if possible.

    Also, high TA is what is driving your PH up. So if you raise the TA back up the PH will rise even more quickly.
    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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    Re: pH keeps yo-yo'ing up and down

    To keep CSI negative and prevent scaling. I already have plaster stains and some of it may be scale, so I'm keeping the pH on the lower half of the range. Am I going about it wrong?

    Thought so on the TA. It did come down to 70 though.
    IG gunite pool size: 12,500 gallons - includes spa with spillover, Polaris vacuum cleaner, Ultrapure Ozonator, inline tab chlorinator that I no longer use
    Filter: Hayward Swimclear Model #4030, 4-Cartridge Filters
    Pump: Century, 2 HP with a Hayward 6060 booster pump
    Date of build: March-April 2014 *NEW* : Test kit: TF-100

  4. Back To Top    #4
    JasonLion's Avatar
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    Re: pH keeps yo-yo'ing up and down

    Of course the best thing to do is to keep CH low, but obviously that isn't always possible.

    If you do need to maintain the PH low, the best thing is to also keep TA low, which will minimize CSI and reduce the rate at which PH rises.

    Keeping PH below 7.5 is a project with no end. It never wants to stay there. Plus you will need to keep TA at 60+. TA will tend to want to go down over time, but you don't want it getting too low.

    One possibility to consider is an automated acid feed system.
    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

  5. Back To Top    #5

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    Re: pH keeps yo-yo'ing up and down

    Very interesting, and good to know that I'm not the only one who finds it difficult to keep pH under 7.5 (whether it is necessary or not).

    I have some baking soda on hand if I need to maintain TA at 60+.

    Thanks Jason.
    IG gunite pool size: 12,500 gallons - includes spa with spillover, Polaris vacuum cleaner, Ultrapure Ozonator, inline tab chlorinator that I no longer use
    Filter: Hayward Swimclear Model #4030, 4-Cartridge Filters
    Pump: Century, 2 HP with a Hayward 6060 booster pump
    Date of build: March-April 2014 *NEW* : Test kit: TF-100

  6. Back To Top    #6

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    Florence, AL
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    Re: pH keeps yo-yo'ing up and down

    What's most puzzling is that the description in OP's signature leads me to believe he's using trichlor pucks. Why on earth would his pH go up?
    33k Gallon IG Freeform Gunite built in 1989 - Renovated Spring 2012 with Diamondbrite Plaster and elevated spa converted to waterfall
    Jandy Aqualink PDA Automation & Control System - Jandy PlusHP 1.5hp Full rated Pump - Hayward 36in Sand Filter - Jandy Aquapure 1400 SWCG
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  7. Back To Top    #7

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    Re: pH keeps yo-yo'ing up and down

    Oh yeah when I first joined I was still using pucks, and put that in my sig. After reading pool school I stopped using pucks and switched to bleach.

  8. Back To Top    #8

    Re: pH keeps yo-yo'ing up and down

    What is your calcium, cya and temperature?

    Also, I would recommend disconnecting the ozone.

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