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Thread: Pool is trouble free, but with low TA.

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    Carolwoodpacific's Avatar
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    Pool is trouble free, but with low TA.

    Today's test as follows...

    FC-5
    CC-0
    PH-7.9
    TA-40
    CYA-25

    My TA has been low for several weeks now. PH is easy to control though, I put six ounces of acid in every week like clock work. Should I worry about the low TA, I hate to put a bunch of baking soda in when the pool is trouble free.

    P.S. I know my CYA is low, it is a constant battle because of the massive amount of rain we get here.
    7000 gallon IG pebble tech (31X7.5 feet) Built 1998.
    Hayward Star Clear Plus C900 cartridge filter with 1 1/4 HP pump.
    TF-100 with speed stir. Liquid chlorinated.

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    Mod Squad YippeeSkippy's Avatar
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    Re: Pool is trouble free, but with low TA.

    Go ahead and add that baking soda, per PoolMath, and a bit of MA to lower your pH. Your TA & pH will level out more if you bring it into line which is important for plaster pool owners to help maintain their CSI in a desired range.
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    Re: Pool is trouble free, but with low TA.

    Oops! Plaster pool. Edited comment.
    7600 gallon; 18'X54" round; vinyl; sand filter and 110V pump, 2-speed.
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    Re: Pool is trouble free, but with low TA.

    I'd be concerned with a few things.....

    Your FC is too high for the CYA

    TA is a little low I'd go up to 50-60,

    pH is a bit too high,

    and the BIGGIE, CH is not reported. Depending on the CH level, you may not be Trouble Free for long..... Have you computed your CSI?

    You may have reached some form of equilibrium, but the numbers are not within specs.....

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    Carolwoodpacific's Avatar
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    Re: Pool is trouble free, but with low TA.

    Today's results after yesterday's PH adjustment.

    FC-4
    CC-0
    PH-7.5
    TA-50
    CH-350
    CYA-25

    This puts my CSI at -.02 according to poolmath.

    I intend on putting in the poolmath recommended amounts of baking soda and CYA today.

    Thanks,

    Joe
    7000 gallon IG pebble tech (31X7.5 feet) Built 1998.
    Hayward Star Clear Plus C900 cartridge filter with 1 1/4 HP pump.
    TF-100 with speed stir. Liquid chlorinated.

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    Re: Pool is trouble free, but with low TA.

    IME, which is like yours, you will raise TA, but then you pH will rise faster, so you'll need more acid, which will lower the TA, etc. I would stick with whatever combo has you adding less acid less frequently. Don't just accelerate the cycle. If there is a lower threshold for TA that none shall pass then we should talk about that, but if the CSI is ok, which it is, and everything is stable, just keep monitoring it occasionally. I test TA once a month along with cya. ymmv of course.

    Edit: My phone keeps wanting to add Miami after csi
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    DaninFLA's Avatar
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    Re: Pool is trouble free, but with low TA.

    do not raise your TA if you have high pH! consider yourself lucky that your pH rise is not too fast. increasing your TA is going to make your pH rise faster and use more acid. don't worry about the recommended TA values...its not an independent issue from pH. if your pH is happy, don't change it.

    if you pH was going down, then yes you would want to raise it so your pH rises from aeration. hopefully you haven't added any baking soda

    - - - Updated - - -

    Quote Originally Posted by YippeeSkippy View Post
    Go ahead and add that baking soda, per PoolMath, and a bit of MA to lower your pH. Your TA & pH will level out more if you bring it into line which is important for plaster pool owners to help maintain their CSI in a desired range.
    not correct. if you raise your TA, your pH is going to want to rise faster. you should ONLY be changing your TA if you have a pH issue. he is already having to add acid to his pool each week to lower his pH, why on earth would we want him to increase his TA and cause faster pH rises and the need for more acid?!

    OP, don't worry about it. keep TA where it is.
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Carolwoodpacific's Avatar
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    Re: Pool is trouble free, but with low TA.

    I think that I will just keep an eye on it for now. Can TA fluctuate naturally? The only thing I put in the water is liquid chorine and acid.
    7000 gallon IG pebble tech (31X7.5 feet) Built 1998.
    Hayward Star Clear Plus C900 cartridge filter with 1 1/4 HP pump.
    TF-100 with speed stir. Liquid chlorinated.

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    DaninFLA's Avatar
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    Re: Pool is trouble free, but with low TA.

    TA decreases as you add acid to lower pH. TA can increase depending on how much TA is in your fill water.

    I wish the recommendations for TA were removed from the recommended levels or at least a footnote or something added. TA should be reviewed based on your pH demands, its a "cause" more than a recommended level. As you can tell from your pool, your TA is low, but you are still getting a rise in pH. others with your TA number could be getting pH drops and having to add borax to raise pH. TA cannot be viewed by itself and adjusted just based on its number and the recommended values. that's what I meant by it not being a stand alone. every pool operates differently. since your pH is constantly rising, you should not increase your TA just to get it within the recommended range.

    if you your pH was constantly going down, then I would recommend to raise your TA, but that's not the case here.

    as far as CSI ratios go, there are lots of variables that affect that. you can adjust your pH accordingly and your CH levels to prevent issues.

    if your TA starts getting too low and your pH starts going down, then you should increase it.
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
    Pool School - Chlorine / CYA Chart; Pool School - Test Kits Compared;

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    Re: Pool is trouble free, but with low TA.

    Quote Originally Posted by Carolwoodpacific View Post
    Today's results after yesterday's PH adjustment.

    FC-4
    CC-0
    PH-7.5
    TA-50
    CH-350
    CYA-25

    This puts my CSI at -.02 according to poolmath.

    I intend on putting in the poolmath recommended amounts of baking soda and CYA today.

    Thanks,

    Joe
    I don't know where you are getting -0.02 because with your numbers and 80F water temperature I get -0.22 in PoolMath. At 88F it's -0.15

    If the pH rise is from carbon dioxide outgassing, then your acid addition will keep lowering the TA. 6 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 7000 gallons will lower the TA by 3.4 ppm so roughly 10 ppm every 3 weeks.

    If you don't try and lower your pH as much, you should use less acid over time, so don't try and go below 7.5 when you add acid.

    You mentioned that your CYA is low because of the massive amount of rain that you get, so implying you get rain overflow diluting your water, but why is your CH not dropping as well? If both your CYA and your CH tend to drop due to water dilution, you may be able to use a mixture of chlorine sources including Trichlor (that will also add acid for you as well as CYA) and possibly Cal-Hypo (for CH). You can, of course, just use chlorinating liquid or bleach and add pure CYA and calcium chloride separately, but it sounds like you have options available to you due to the large amount of water dilution. Just keep the CH on the high side to protect your plaster if you intend to keep the TA level low. Regardless of whether you add acid manually or use Trichlor, you have to carefully manage your TA level since it will drop from either acid source.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Carolwoodpacific's Avatar
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    Re: Pool is trouble free, but with low TA.

    Thanks for the clear explanation Dan and Chem Geek.
    7000 gallon IG pebble tech (31X7.5 feet) Built 1998.
    Hayward Star Clear Plus C900 cartridge filter with 1 1/4 HP pump.
    TF-100 with speed stir. Liquid chlorinated.

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