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Thread: Is this an abnormal amount of acid for a spa?

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    Is this an abnormal amount of acid for a spa?

    I am having trouble reducing TA and lowering pH, despite following the procedures described on this site.

    Spa is 290 gallons.

    CH is 300, TA is at 110 and pH is at 8.2 despite adding a lot of acid.

    I'm using the aeration/acid approach, and TA started at 220, so it's making progress, but is it normal to use 5/6ths of a bottle of acid (so far) for such a small amount of water?

    The only chemicals in the water so far are a bit of dichlor, enough borax to get to 50 ppm, and a ton of acid.

    The water looks, feels, and smells great, but the acid consumption seems really high.

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    Re: Is this an abnormal amount of acid for a spa?

    Deleted my post, decided I really didn't know what I was talking about. I think this is a borate issues and I don't know too much about that!
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    Richard320's Avatar
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    Re: Is this an abnormal amount of acid for a spa?

    Quote Originally Posted by tetragon
    I am having trouble reducing TA and lowering pH, despite following the procedures described on this site.

    Spa is 290 gallons.

    CH is 300, TA is at 110 and pH is at 8.2 despite adding a lot of acid.

    I'm using the aeration/acid approach, and TA started at 220, so it's making progress, but is it normal to use 5/6ths of a bottle of acid (so far) for such a small amount of water?

    The only chemicals in the water so far are a bit of dichlor, enough borax to get to 50 ppm, and a ton of acid.

    The water looks, feels, and smells great, but the acid consumption seems really high.
    Insufficient data.

    What is the chlorine level? If the FC level is way high, above 10 or thereabouts, your pH reading will be off.

    Second, the tester only goes to 8.2, so who knows what the starting pH really was? It coulda been 10 for all you know!

    Third, what is "a lot of acid"? 5/6 of what size bottle? A quart? A gallon?
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    Re: Is this an abnormal amount of acid for a spa?

    For a 290 gallon spa, it will take 17 ounces (weight) of Borax to raise the borates to 50 ppm and it will also take 8.1 ounces (volume) of 31.45% muriatic acid to compensate for the pH increase due to the Borax.

    It will take another 8.1 ounces of 31.45% muriatic acid to lower the TA by 110 ppm for a total of 16.2 ounces of 31.45% muriatic acid, which is equivalent to 22 ounces of dry acid (sodium bisulfate).

    If your bottle of acid is 24 ounces of dry acid, then that is about right (5/6 X 24 = 20 ounces).

    I prefer to use muriatic acid rather than dry acid, especially when adding a lot of acid, to avoid adding high levels of sulfates.

    In the future, you might want to consider using boric acid instead of Borax because boric acid is mostly pH neutral. 290 gallons would take 11 ounces (weight) of boric acid to achieve 50 ppm.

    http://www.poolcalculator.com/

    http://www.chemistrystore.com/search.cg ... boric+acid

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