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Thread: Very low PH

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    Very low PH

    Hi, my pool have a very low PH, i add PH + 3 times and still the same result, i bring a water sample to the pool store and the guy recommend to drain the pool and refill, did someone know what to do except the drain solution, hi have a well and it will takes 2 weeks to refill.

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    Re: Very low PH

    How low is your ph?
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    Mod Squad Bama Rambler's Avatar
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    Re: Very low PH

    Draining the pool because of low pH isn't necessary. DO you know what the TA is?

    If the TA and/or pH is very low it takes a lot of chemical to get it to move.

    How much pH+ have you added?
    Dave J. TFP Moderator
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    Christian's Avatar
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    Re: Very low PH

    What is your chlorine level? If your chlorine level is high it can cause your pH to read low.

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    Christian's Avatar
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    Re: Very low PH

    Also if you have the tf100 or k2006 kit you can add some reagent #7 to neutralixe the chlorine and get an accurate pH reading. This is assuming that your pool is super chlorinated.

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    Re: Very low PH

    We need a full set of readings to provide you with the best advice.

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    dmanb2b's Avatar
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    Re: Very low PH

    Quote Originally Posted by Christian
    What is your chlorine level? If your chlorine level is high it can cause your pH to read low.
    Hey Christian, did you mean read high? If it's a phenol red PH test, FC over 10ppm will cause the test to read falsely high.


    To OP: As JamesW said...we need a full set of test results to really help you. Draining the pool can be avoided and is rarely advised unless there are other chemistry issues.
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    Christian's Avatar
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    Re: Very low PH

    My mistake, I was under the impression that high chlorine could make the pH read incorrectly high or low.

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    Re: Very low PH

    A couple things to keep in mind:
    1) Anything below the lowest pH reading on the scale will read as that. So, despite calculating how much pH increaser you need to add, it may not be enough. You might be at 6.2 not 6.8 when you start. Which brings up
    2) pH is a logarithmic value. It's not a straight line. One pound of soda ash may raise pH from 6.8 to 7.2, but it might only raise 6.2 to 6.4.

    A full set of test results, preferably some you've taken yourself, with a drop test, not strips, would go a long, lomg way towards solving your problem.
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    Re: Very low PH

    My PH is below 6.8, i already add 1.5 pound of PH + without any result... My Chlorine is level is none.

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    Re: Very low PH

    Test pH, dose, let the pump run for 45 min. Repeat this process until your pH gets to 7.2

    What Richard said is important, so understand that it will take what it takes, and that may be a lot of pH+ (or whichever product you use to raise it).

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    Mod Squad Bama Rambler's Avatar
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    Re: Very low PH

    Without knowing what size your pool we have no idea how much 1½ lbs would be but it's not a lot if your pH is really low.

    It would help to know the TA too. You may need to adjust that as well.
    Dave J. TFP Moderator
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    Re: Very low PH

    Quote Originally Posted by Christian
    My mistake, I was under the impression that high chlorine could make the pH read incorrectly high or low.
    The quote from Taylor's Pool & Spa Water Chemistry booklet on the issue of a high FC causing a false high pH reading is as follows:

    FALSE READINGS: high levels of chlorine (usually > 10 ppm) will quickly and completely convert phenol red into another pH indicator (chlorphenol red). This new indicator is a dark purple when the water's pH is above 6.6. Unfortunately, some pool operators mistake the purple color for dark red and think the pool water is very alkaline and wrongly add acid to the pool.

    When a sanitizer level is not extreme, only some of the phenol red may convert to chlorphenol red. However, purple + orange (for example, pH 7.4) = red. This error is more subtle as no purple color is observed and the operator does not suspect that a false high pH reading has been produced. Some operators neutralize the sanitizer first by adding a drop of chlorine neutralizer (i.e. sodium thiosulfate). However, thiosulfate solutions have a high pH and, if heavily used, may cause a false higher sample pH.
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    Re: Very low PH

    What is TA ? Total Alacanity?

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    UnderWaterVanya's Avatar
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    Re: Very low PH

    Quote Originally Posted by Easyofff
    What is TA ? Total Alacanity?
    Yes - see here:
    pool-school/read_before_you_post
    (Basic info on how to setup a signature and what chemical tests you should post with what abbreviations)

    And here:
    pool-school/swimming_pool_definitions_abbreviations
    (More details on other abbreviations you may run into)

    And maybe here:
    pool-school/pool_water_chemistry
    (Basics of what each chemical does etc.)
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    Re: Very low PH

    We need all the chemical levels in order to tell you what you need. Have the pool store run another sample for now and give us the following:

    FC= Free Chlorine
    TC= Total Chlorine
    TA= Total Alkalinity
    CH=Calcium Hardness
    CYA= Cynaric Acid= Stabilizer
    pH= Acidity/Alkalinity

    For the pool store to recommend draining the water tells me that your CYA might be too high and the solution to fix that problem is draining. If the pool store could sell you chemicals to fix your water without draining, that would be in their best interest. It could be that they don't have a clue about how to fix it, and new water is their only suggestion.
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    dmanb2b's Avatar
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    Re: Very low PH

    In the mean time, it's time to read through pool school. The links have been provided, but the button on the upper right hand side of this page or the link in my sig will take you there We need information to help you. Size of pool, how you are testing, etc. Full set of test results please, below is a guide as to what we need to better help you

    what-we-need-to-know-to-answer-your-questions-t10341.html
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