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Thread: Ph v ta

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    Default Ph v ta

    I have what might sound like a stupid question. My PH tends to hold pretty well. But my TA tends to run high, around 160. When I add acid to lower TA, it drives my PH down also. Is there a way to lower TA without changing my PH? Which is more important to worry about. I have a plaster pool which I just re-filled to lower CYA. It looks fantastic right now. Chlorine level is steady and the water is very clear. I have checked it several times a day and all is good except the TA is high.

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    CarlD's Avatar
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    Default Re: Ph v ta

    You said you have a plaster pool? That changes things.

    You need to start lowering your T/A to 120-125 as your upper limit. For a vinyl pool 180 seems to be the safe upper end.

    Look up our thread on lowering T/A via the ratchet method (you "ratchet" it down).

    You lower pH with acid, which brings T/A down with it. Then you aerate to raise pH without T/A rising again.
    Now you "ratchet" T/A down by lowering pH again, then aerating to raise it.

    I'd aim for 100 as my target if I were you.
    Carl

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    Default Re: Ph v ta

    OK...I add acid to lower PH which lowers TA. That much I understand. I do it in stages so as not to go to far.But how do I "aerate" the pool. I have never done that and am not sure what that means.

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    Default Re: Ph v ta

    waskydiver, not so interested in perfect numbers as much as I am concerned that with the plaster pool, the high TA could cause problems.

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    Default Re: Ph v ta

    To aerate, you can turn your return jet eyeballs upward to create rippling/bubbling on the surface. Or throw in a bunch of kids to play around. Anything that causes splashing will aerate.

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    Default Re: Ph v ta

    I've never heard of aeration before, does anyone have an idea how it raises pH??

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    Default Re: Ph v ta

    Well thats easy enough...thanks

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    Default Re: Ph v ta

    Quote Originally Posted by wposton84 View Post
    I've never heard of aeration before, does anyone have an idea how it raises pH??
    Not sure of the chemistry, but there's a gasification process that turns an acid into a hydroxide by the removal of, I think it's CO2. Chem_Geek has the whole chemistry of it down pat.

    If your T/A and your CH are both too high, it's easy to get cloudy water. For plaster pools, usually a CH of 200 to 400ppm is recommended. But if your CH goes to 500pm and your T/A rises, then you'll get cloudy water.

    Most vinyl pool owners don't have high calcium so it's not a problem if T/A is higher.
    Carl

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    Default Re: Ph v ta

    The short answer is that carbon dioxide in water is carbonic acid so when you are removing carbon dioxide from the water you are effectively removing carbonic acid -- removing an acid raises the pH. For technical reasons I won't get into here, the TA does not change.

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    Default Re: Ph v ta

    Quote Originally Posted by chem geek View Post
    The short answer is that carbon dioxide in water is carbonic acid so when you are removing carbon dioxide from the water you are effectively removing carbonic acid -- removing an acid raises the pH. For technical reasons I won't get into here, the TA does not change.
    Thanks for the SUPER-simple and clear explanation, Richard. I think I finally understand how the aerating raises pH!
    Carl

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