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Thread: Fighting with PH and TA

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    Fighting with PH and TA

    FC 7
    CC 0
    PH 7.7
    TA 60
    CH 375
    CYA 55

    I've run into a problem with my TA. This is an older pool and the PH is fairly constantly rising, which I've been fighting with MA. The pool has some moderate to severe calcium scaling perpetrated by the previous owner, so I've been trying to keep the Ph around 7.2. In addition to going through 2 gallons of acid a month doing this, my TA has fallen from around 90 to 60 over the past few months.

    This has not seemed to assist with my PH rising troubles very much, maybe slightly. Even with the Ph having crept back up to 7.7 when last measured, my CSI has gone down to -8.8 with the lower TA.

    Since the water temp is going to be going up soon, does this need attention, or can I leave the TA where it is? And if anyone has any theories as to why my pool is a Ph increasing MACHINE I'd be all ears as well. Thanks!
    15260 gal IG plaster pool
    Swimquip HRS16-01 Sand Filter (20-28 gpm)

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    Melt In The Sun's Avatar
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    Re: Fighting with PH and TA

    Do you have a SWG or fountain/waterfall? Those are the most common pH pusher-uppers.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
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    Re: Fighting with PH and TA

    No to both, sir. I also do not point the return jets up, and the pool isn't in use yet. I can only imagine the pain I'm in for once it starts getting used and aerated.
    15260 gal IG plaster pool
    Swimquip HRS16-01 Sand Filter (20-28 gpm)

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    Mod Squad JohnT's Avatar
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    Re: Fighting with PH and TA

    2 gallons of MA a month isn't really a lot of acid IMO. You may find that more frequent pH corrections to stay below 7.4 might actually lead to decreased use once you drive your TA down a little.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Fighting with PH and TA

    Some pools just take more acid than others. I think that you may find that your TA will probably find a point it likes and sort of hang around there as long as you keep addressing the pH rise by adding acid when needed. Mine is that way. My TA like to be at 60 ppm and tends to stay there. All I worry about is controlling the pH by adding the amount of acid that I need to add.

    If your TA continues to fall to levels of 50 or below, you might consider adding borates to your pool as a secondary buffer system.

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    linen's Avatar
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    Re: Fighting with PH and TA

    Quote Originally Posted by Agentbolt
    Even with the Ph having crept back up to 7.7 when last measured, my CSI has gone down to -8.8 with the lower TA.
    I am confused...CSI of -8.8, how would you get that? Using poolcalculator.com, I get a CSI of 0 using ph of 7.7, TA of 60, CH of 375, 55 cya, 0 salt, 0 borates and a temp of 80F. What am I missing/what is the problem with your CSI?
    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: Fighting with PH and TA

    Quote Originally Posted by linen
    Quote Originally Posted by Agentbolt
    Even with the Ph having crept back up to 7.7 when last measured, my CSI has gone down to -8.8 with the lower TA.
    I am confused...CSI of -8.8, how would you get that? Using poolcalculator.com, I get a CSI of 0 using ph of 7.7, TA of 60, CH of 375, 55 cya, 0 salt, 0 borates and a temp of 80F. What am I missing/what is the problem with your CSI?
    You should be confused, my temperature was set way too low on the pool calculator. My CSI is actually only -.21. (also obviously I had the decimal point in the wrong place).

    So as long as my TA doesn't dip to like 50 I'm fine?
    15260 gal IG plaster pool
    Swimquip HRS16-01 Sand Filter (20-28 gpm)

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    linen's Avatar
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    Re: Fighting with PH and TA

    I am not an expert on CSI (nor do I have a pool that cares too much, I have a vinyl liner) but I would not worry about your CSI too much. I wouldn't even worry about a low TA since it sounds like your pool has had problems with scaling which is on the other end of the spectrum of CSI. I would keep adding acid when needed and see where your TA ends up. With your slightly higher CH, a low TA may not be a bad thing.
    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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    Aquatica's Avatar
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    Re: Fighting with PH and TA

    your levels look fine. once there is scale the only thing you can do is have it removed. I've never found lowing the pH or using anything else in the water being able to remove the already formed scale. when we have a client who wants scale or stains removed from the pool finish we do a drain and acid wash (if pool finish can take an acid wash). Most likely you probably have scale on the tiles. This can be easily removed with pool tile cleaner and a brush without draining.

    can't see pH going up much at TA of 60 but maybe pH will stabilize at TA of 50..or 55. other things like shocking a pool with CalHypo will raise pH.

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    Re: Fighting with PH and TA

    I've never found lowing the pH or using anything else in the water being able to remove the already formed scale.
    I think Richard320 is slowly reducing his scale by maintaining low pH.

    For someone in the industry, his approach may not be practical but, remember, this is a pool owners forum and we can often use long-term techniques that folks in the business cannot.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Aquatica's Avatar
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    Re: Fighting with PH and TA

    Quote Originally Posted by duraleigh
    I've never found lowing the pH or using anything else in the water being able to remove the already formed scale.
    I think Richard320 is slowly reducing his scale by maintaining low pH.

    For someone in the industry, his approach may not be practical but, remember, this is a pool owners forum and we can often use long-term techniques that folks in the business cannot.
    This is true. we really don't have the time to do some of the time consuming fixes. we would need to live at the pool every day. what ever works.

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