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Thread: Is this too much dry acid to add to a hot tub.

  1. Back To Top    #1

    Is this too much dry acid to add to a hot tub.

    When I do a water change my ph is always around 8.4 and TA 220 with a Calcium Hardness of 220.

    To bring my Ph and TA down I add dry acid then run pumps and air for 30-60mins and then test and repeat the process. On my recent refill I added the dry acid in the following quantities
    200g , 120g, 70g, 50g, 25g untilI got the TA down to 50 with a ph of 7.5 which appears to give balanced conditions. The capacity of the hot tub is 1950 litres.

    Could I have added more dry acid in one go to reduce the time to geat the water conditions correct or am I adding too much in one go. I have read somewhere that you should not add any more than 100g in one go.


  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Is this too much dry acid to add to a hot tub.

    Adding a total of 465 grams of dry acid to 1950 liters of water would lower the TA from 220 ppm to 127 ppm so I'm not sure how you got down to 50 ppm. If you were to add this all at once starting with a pH of 8.4, then the pH would drop as low as 6.5 if there were no carbon dioxide outgassing. You could add 200 grams of dry acid which would lower the pH to 7.0 and the TA by 40 ppm to 180 ppm. With aeration, it shouldn't take long for the pH to rise when you could then add more dry acid.

    So while you can be more aggressive in your dosing than you have been, I wouldn't add it all at once.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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  3. Back To Top    #3

    Re: Is this too much dry acid to add to a hot tub.

    Thanks for the quick reply.
    I think perhaps before I get too agressive with my dosing it may be time to invest in some new scales. I am confident that my water testing is OK but possibly the accuracy of my weighing leaves something to be desired.

    Thanks again

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