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Thread: TA

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    TA

    I just refilled my 250 gal hot tub, our water is quite high in TA (tests about 220ppm) but neutral. I understand the logic behind lowering the pH to 7.2 to lower TA but 'aeration' is not an option to help raise the pH back up. (It's too cold here to run the tub with the cover off.) Should I add back some baking soda? Should we just use the tub and raise the pH that way? I assume pH 7.2 would feel fine, though my Taylor test kit doesn't read below 7.2 so hard to know if I've overshot. Any thoughts?
    250 gal Cove spa. with ozonator. Northern Vermont. Outdoors but no direct sunlight.

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    Richard320's Avatar
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    Re: TA

    Quote Originally Posted by Lee In VT View Post
    I just refilled my 250 gal hot tub, our water is quite high in TA (tests about 220ppm) but neutral. I understand the logic behind lowering the pH to 7.2 to lower TA but 'aeration' is not an option to help raise the pH back up. (It's too cold here to run the tub with the cover off.) Should I add back some baking soda? Should we just use the tub and raise the pH that way? I assume pH 7.2 would feel fine, though my Taylor test kit doesn't read below 7.2 so hard to know if I've overshot. Any thoughts?
    No, don't add baking soda. That will just raise the TA. What is the pH reading? You say the TA is 220, but "neutral". What is neutral? The pH? Or is the pH below 7.2?

    If the pH is already below 7.2, you can probably raise it in a short period of time by just running the spa and getting in it. For that matter, just running it with the cover on will do the same thing. You already bathe in the fill water, so I doubt it's going to cause any skin problems. And people tend not to swim around in a spa, so eye irritation shouldn't be a problem, either.
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    Re: TA

    Yes, you can do what you propose of letting the pH rise when you soak (do not add baking soda to raise pH, however, since it mostly raises TA and you don't want to do that). Just note that with the high TA, the pH may rise fairly quickly. I wouldn't add any calcium to increase the CH until the TA gets lower. That way you can avoid the risk of calcium carbonate scaling even if the pH rises. Of course, if your CH is already high from the fill water then there's not much you can do except try to keep the pH from getting too high.

    The Taylor kits read pH to 7.0 or 6.8 depending on the kit. I didn't think there was one that bottomed out at 7.2. With the lowest pH in the kit of 7.0, you can distinguish 7.2 but don't know if 7.0 is at 7.0 or below.
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    Re: TA

    I just answered in this post the same question you posted in another thread. Please only post your questions in one place so we don't have to track/manage multiple threads with the same question.
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    Re: TA

    Lee In VT,

    Duplicate post deleted and posts merged. Please start your own thread when you have a question and only post one message. Butterfly
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    Re: TA

    Sorry, I got confused as to which forum I was posting to and couldn't find the one I thought I had sent, so I figured it failed. Also, contrary to my earlier statement, my pH tester does go down to 6.8, I was wrong. My fill water is pH 7.5 (what I meant by neutral) with TA of 250ppm. I've lowered the pH to 7.2 with muriatic acid though the TA remains high (~220). So if I understand, just ignore the TA for now and keep adjusting the pH which will rise with use. Nothing else to do to lower TA meanwhile. I have dry sodium bisulfate as well, which I could use. Is there any advantage over muriatic acid, other than ease of use? (maybe this question should be a new thread, I'm new to this site.) Thanks for your help.
    250 gal Cove spa. with ozonator. Northern Vermont. Outdoors but no direct sunlight.

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    Re: TA

    Dry acid (sodium bisulfate) increases sulfates. For a spa where you change the water, that's probably OK. For a pool, especially with plaster, Muriatic Acid is better. So use either acid for your spa. If you use Muriatic Acid, you can certainly use the half-strength 15-16% variety since it fumes less and you don't need to use very much.
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