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Thread: pH & TA lowering, help please

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    pH & TA lowering, help please

    Hi All,

    I'm trying to lower my TA (180), I am following the guide on here on how to do so. I am also using poolmath

    Yesterday my pH (7.8) using the calculator I initially tried to lower it to 7.5 just to take it easy as this is the first time I have done this process. I calculated using the poolmath that I needed to add ~700ml of acid, which I did.

    I retook the pH again an hour later with pump going, it appeared to not change at all (7.8), so I added a further 600ml of acid. Decided to leave it overnight. I also did an acid demand test which basically indicated I needed to add the same amount again.

    This morning I checked pH (7.6) so it appears that despite the amount of acid I am putting in its not doing a lot.

    I also notice when I entered the TA in pool math it readjusted the amount of acid I need (significantly increased it), I can understand this but I want to check if this sounds right before I go plunging more acid into the pool?.


    Also on a side note can someone explain why aeration raises pH? just curious for my information

    thanks
    3yr old 60,000L (15.8k Gal) Fibreglass IG, Viron eVo P600 pump, Hayward Pro Series Filter (glass media), Zodiac SWG, Zodiac VX55 4WD, Solar Heated

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    Re: pH & TA lowering, help please

    Follow the article precisely.... get your pH down to 7.0 - 7.2 regardless of how much acid it takes.

    The acid/aeration process to lower TA:
    1. Add acid to lower your PH to between 7.0 and 7.2 (this also lowers TA)
    2. Aerate until PH rises to around 7.6 (the only way to raise PH without also raising TA)
    3. Repeat steps 1 and 2 until you reach the desired TA.



    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: pH & TA lowering, help please

    Aeration increases the rate of CO2 outgassing from the water.

    From what you are describing you are not really aerating in the sense that the aeration needs to break the surface of the water. Just running your pump will be slow.

    The easiest way to provide aeration is the invert the return jets upwards so that the water is being returned via the breaking of the surface of the water.
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
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    Re: pH & TA lowering, help please

    Hi Jezza,

    As duraleigh pointed out, I'm firstly trying to get my pH down so I can start the aeration, I'm waiting for it to get to 7.0-7.2 range, then I can use the spa jets at the side of the pool to provide aeration. I didn't want to aerate before getting the pH down until i know my pH is down for sure.

    Its taken a heck of a lot of acid (2.7L) so far, ...as of now I'm sitting around 7.2-7.4 so it looks like i'm getting there, I was just cautious having not done this before
    3yr old 60,000L (15.8k Gal) Fibreglass IG, Viron eVo P600 pump, Hayward Pro Series Filter (glass media), Zodiac SWG, Zodiac VX55 4WD, Solar Heated

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    Re: pH & TA lowering, help please

    You are wise to take it slowly. Pool math can assume your addition corrected. You may have to re-enter your new readings.

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    Re: pH & TA lowering, help please

    No worries Hawknz- sorry I can see what you meant now. Yes good advice to bring it down slowly but yes bring it right down to 7.0-7.2.
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
    K-2006

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    Re: pH & TA lowering, help please

    An Update:

    I have successfully managed to lower my TA from 180 - 110 since my original post. Albeit using 8 litres of acid (2.1 gallon).

    I'm not sure whether I should continue the same process to get it down to 80 or allow this to happen naturally? (or does it happen naturally?).
    3yr old 60,000L (15.8k Gal) Fibreglass IG, Viron eVo P600 pump, Hayward Pro Series Filter (glass media), Zodiac SWG, Zodiac VX55 4WD, Solar Heated

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    Re: pH & TA lowering, help please

    You can keep actively trying to lower TA by lowering pH to 7.0 and adding a source of aeration to help drive the pH up faster, then repeat until you get to the desired TA. However, if you simply maintain pH by just adding acid once your pH rises to above 7.8 it will happen over time and eventually your pH rise will slow to a crawl and your TA will be at the proper level for your pool. You're not that far off from a plausible TA to maintain so I would go that route.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
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    Re: pH & TA lowering, help please

    thanks JVTrain

    I carried on and finally today I have reached my goal (80)

    Full Test Results:

    pH: 7.4 (will allow to rise)

    TA: 80

    FC: 5.5

    CC: <0.5

    CH: 200

    CYA: 70

    Very pleasing to see them all falling into line, just need to raise the CH a touch.

    Thanks All for the help
    3yr old 60,000L (15.8k Gal) Fibreglass IG, Viron eVo P600 pump, Hayward Pro Series Filter (glass media), Zodiac SWG, Zodiac VX55 4WD, Solar Heated

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