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Thread: pH shot up (and so did TA) way more than anticipated

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    pH shot up (and so did TA) way more than anticipated

    FC: 4/5
    pH: 7.8
    TA 120

    Last night, our pH was 7.2, with TA at about 80. I used the pool calculator and calculated that I needed 32 ounces of soda ash to increase ph to 7.5 and TA by about 9.1.

    This morning, I just checked it and our pH is 7.8 and TA 120. I know this seems to still be within parameters, but I am wondering why it went up so much. Don't really want either of them going up anymore, however. We haven't swam, aerated or anything to make the pH climb so much. Last time when I added soda ash at the same numbers, using the calculator, it worked like a charm. (It's always a possibility I calculated the TA incorrectly this time around I guess.)

    The pool water looks clear. Just wondering if I should do anything at this point, or leave it be and see where it takes us.
    7+ years, inground, 25,000 gallon, vinyl, sand filter.

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    Re: pH shot up (and so did TA) way more than anticipated

    There is no rush to adjust anything at the moment as the pH and TA are in range although at the upper limit. Make sure the water has been circulated for an hour and test again to see if they repeat.

    Does the pH normally drop for you? If so, leave it alone and keep track of it every day to see what happens. If not, then you might want to lower the pH to 7.5 and see how long it takes to rise again. If the pH wants to climb faster than normal, lower it to 7.2 each time and that will drive the TA lower if your fill water is not too high in TA.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    Re: pH shot up (and so did TA) way more than anticipated

    Quote Originally Posted by ping
    There is no rush to adjust anything at the moment as the pH and TA are in range although at the upper limit. Make sure the water has been circulated for an hour and test again to see if they repeat.

    Does the pH normally drop for you? If so, leave it alone and keep track of it every day to see what happens. If not, then you might want to lower the pH to 7.5 and see how long it takes to rise again. If the pH wants to climb faster than normal, lower it to 7.2 each time and that will drive the TA lower if your fill water is not too high in TA.
    You know, I just realized I tested when the water was only circulating for about 30-45 minutes. I probably should have waited longer. You're right. I will retest a little later to see what I get.

    Our pH actually has a tendency to drop it seems. Not sure if it's from the recent waves of rain we have had, not enough sun lately, or what, but so far that seems to be the trend. I will leave it be for now and see where it goes from here We are getting lots of sun today though.

    Is there a time period you should wait between introduction of soda ash for raising the pH and muriatic/dry acid to lower it if it gets too high? Hypothetical: Say I added soda ash last night and our pH shot threw the roof where it became too high and I needed to counteract that...Could I add muriatic acid shortly thereafter to lower the pH? It can't only be a half an hour is it?

    Also, what do you mean by "fill water" here: "that will drive the TA lower if your fill water is not too high in TA."
    7+ years, inground, 25,000 gallon, vinyl, sand filter.

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    Re: pH shot up (and so did TA) way more than anticipated

    I would let the pool run for a good hour before adjusting with acid. It wont hurt to run for only an hour and you want to make sure that you don't compound one error with another. If you made a major mistake with the soda ash, then that is another subject not to be confused with slightly out of range recommendations.

    The fill water is the water that you use to fill the pool when it gets too low from evaporation, splash out, etc. If the fill water is high in TA, then the fill water will tend to raise the TA in the pool when the water is added. Since your TA was 80 ppm, I suspect that the fill water is not high in TA, and with time, acid additions will lower the TA on its own.

    Watch the pH closely for now, and if it rises above 7.8 use some acid to lower it to 7.5.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

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    Re: pH shot up (and so did TA) way more than anticipated

    Quote Originally Posted by ping
    I would let the pool run for a good hour before adjusting with acid. It wont hurt to run for only an hour and you want to make sure that you don't compound one error with another. If you made a major mistake with the soda ash, then that is another subject not to be confused with slightly out of range recommendations.

    The fill water is the water that you use to fill the pool when it gets too low from evaporation, splash out, etc. If the fill water is high in TA, then the fill water will tend to raise the TA in the pool when the water is added. Since your TA was 80 ppm, I suspect that the fill water is not high in TA, and with time, acid additions will lower the TA on its own.

    Watch the pH closely for now, and if it rises above 7.8 use some acid to lower it to 7.5.
    Thank you Just got some dry acid (pH Down) from Home Depot just in case but hoping I don't have to use it.
    7+ years, inground, 25,000 gallon, vinyl, sand filter.

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    Re: pH shot up (and so did TA) way more than anticipated

    We recommend Muriatic Acid over ph down since it is cheaper and add less other stuff to the pool (sulfates in the case of ph down), but the ph down is fine.

    Are you certain of your pool volume? Observations like you made that repeat over time often cue owners into realizing their pool is not as big as they thought/were told.

    Either way I wouldn't worry about your TA for now. When/if your ph goes up to 7.8, lower it back down to 7.2 with MA or ph down and your TA will end up finding it's "happy place".
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: pH shot up (and so did TA) way more than anticipated

    Quote Originally Posted by linen

    Either way I wouldn't worry about your TA for now. When/if your ph goes up to 7.8, lower it back down to 7.2 with MA or ph down and your TA will end up finding it's "happy place".
    Oh, I totally preferred muriatic acid. However, after reading in Pool School how dangerous muriatic acid can be if handled improperly, and how dry acid is easier to handle, I got nervous and didn't want my husband messing with MA if there was an alternative

    Do you mean when my pH goes higher than 7.8? It's been at/about 7.8 (or could be 7.7, always hard to tell) consistently since this morning. I just retested and it didn't budge. I was going to just let it go for a bit and make sure it doesn't increase higher than 7.8, and if so, I was going to add the pH Down.

    What will adding sulfates do?
    7+ years, inground, 25,000 gallon, vinyl, sand filter.

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    linen's Avatar
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    Re: pH shot up (and so did TA) way more than anticipated

    Just don't let ph get above 8 and you should be okay.

    Quote Originally Posted by suziequsie2945
    What will adding sulfates do?
    Per JasonLions post here:
    There can be a problem with sulfate buildup from using very large amounts of dry acid. If sulfate levels get high enough they can damage the coating on the SWG cell plates and potentially cause plaster problems as well. This is normally only an issue if you are using dry acid constantly, as low levels have no real impact.
    So it seems since you have a vinyl liner and no swg, there may be no real risk, but it still goes somewhat against only adding to your pool what your pool needs.

    So, in my opinion, if you only occasionally have to use dry acid I doubt it is a problem, but if lowering ph becomes a constant event, then I would switch to MA to avoid potential issues. Care needs to be taken in handling MA, but most of us on here use it as our preferred ph lowering solution.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: pH shot up (and so did TA) way more than anticipated

    I'm with Linen on this. My first thought was that you overestimated your pool volume. Worth checking out.
    13'x22'x52" 8,000 gallon ProSeries Pool with Borates
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