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Thread: pH in Hot Tub too High? Or just right? Who knows.....

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    Join Date
    Feb 2015
    kentwood, Michigan

    pH in Hot Tub too High? Or just right? Who knows.....

    I have a 355 gallon Hotsprings Sovereign hot tub with an ozonator. Here are my current readings:

    FC: 2 ppm
    TA: 60 ppm
    CH: 150 ppm
    pH: it could be 7.4 or 8.2, depends on the test.....

    So, after going through some growing pains the first time I filled the tub, I then spa purged, drained, cleaned, and refilled the tub. Over the course of a day, I brought the TA down with muriatic acid by adding small amounts using the pool calculator, and then testing the pH and TA. While this was happening, I was surprised that my pH never really dropped a whole lot, even just minutes after adding the acid. I would say that the pH stayed right around 8, with the jets running the whole time. According the the calculator, I should have seen significant drops in pH initially after adding the acid, and then it should have crept back up with the jets on. Is my pH staying high just because I ran the jets too much? If this is the case, than any time someone uses a hot tub with the jets on, you would have to add acid. Also, I've attached photos of the pH test from two different kits, one is the Taylor kit, and the other is brand new from the spa store. The Taylor looks to me to be good (7.6-7.7), while the other still reads a solid 8.2. Yesterday, I though that because my FC was almost 7 ppm that the pH test was reading false on the non-Taylor test kit, but today, with a FC of 2, it is still reading 8.2. I guess I am just frustrated that I can't get a consistent reading for pH, and therefor I don't know how to respond. Sorry for the rant, any advice would be appreciated. IMG_0420.jpgIMG_0418.jpg

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: pH in Hot Tub too High? Or just right? Who knows.....

    The upper PH test photo shows the purple you get when the FC level is too high for the PH test to work correctly. The lower one shows the correct PH. It looks like the lower test is a Taylor test, which is very well buffered against reasonably high FC levels. The upper photo is clearly not Taylor. None of the other brands buffer the PH test against high FC as well as Taylor does. Some of the other brands pretty much don't buffer against FC almost at all.

    When in doubt, trust the Taylor results over just about anything else.
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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: pH in Hot Tub too High? Or just right? Who knows.....

    Quote Originally Posted by JasonLion View Post
    When in doubt, trust the Taylor results over just about anything else.
    +1 My thoughts exactly.

    Don't confuse yourself with multiple test kits.
    Jason, TFP Moderator
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  4. Back To Top    #4

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: pH in Hot Tub too High? Or just right? Who knows.....

    What is your source of chlorine? You should have some Cyanuric Acid (CYA) in the water or else the chlorine will be too strong. If you start out using Dichlor and then switch to using bleach after the CYA has built up to around 30 ppm (so after around 33 ppm FC has been cumulatively added), then that would work. If you just started out using bleach (or any other hypochlorite source of chlorine) then the active chlorine level will be too strong.
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