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Thread: Pool calculator help

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    Pool calculator help

    I have been trying to lower my TA and have managed to get it from 200+ down to 180 with 1 gal of muriatic acid but it seems i should get it lower. But the calculator doesn't tell me to add anything further. Why?

    10,000 gallon
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    NC KANSAS44

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    whoozer's Avatar
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    Re: Pool calculator help

    Not sure same thing happened to me.

    Experts??
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    Re: Pool calculator help

    If you read under the TA part of the calculator, it says to add muriatic acid to lower the pH to 7-7.2, then aerate the water to increase the pH. Then, you repeat the process until you have your TA where you want it.

    What are you looking to have the calculator tell you besides how much acid to add to get the pH to 7.0? Thats really all you need to know. There is no chemical you add to lower the TA, per se. It's just a matter of lowering the pH (which lowers the TA as a by product) and then bringing the pH back up using non chemical means.
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    Re: Pool calculator help

    My current pH is already 7.2. I guess the short answer is I can lower it .2 more and hope it drops my TA by 80?
    10,000 gallon
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    NC KANSAS44

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    Melt In The Sun's Avatar
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    Re: Pool calculator help

    No way a .2 pH change will alter your TA that much. You just have to aerate the water and wait for pH to rise (this will not affect your TA), then lower the pH with acid (lowering TA). Really, aeration isn't necessary since pH will rise on its own with high TA, but aerating will speed up the process. I lowered my TA from 250 to 90 over several months just by adding acid whenever the pH got high.
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    frustratedpoolmom's Avatar
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    Re: Pool calculator help

    You are using the calculator wrong, and/or don't seem to understand how to lower the TA...

    You calculate a dose of muratic acid to lower the PH to 7.2. Then you begin aerating the water. The acid will lower BOTH the Ph and the TA. The aeration will raise the PH back up to 7.6ish. Then you repeat the acid addition and aeration, noting the change in TA with each acid addition. This process can take awhile - depending on your source for aeration it can take several days. Eventually the TA will drop into range, and the aeration gets your PH where it needs to be.

    Hope this helps.
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    Re: Pool calculator help

    The TA will drop by an amount solely determined by the amount of acid that you add and you can see this in the "Effect of adding chemicals" section at the bottom. One cup of Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons will lower the TA by 3.1 ppm. The aeration just lets you get the pH back up (with no change in TA) so that you can add more acid. Otherwise, if you were to just add acid for a large TA move, the pH would end up getting too low.
    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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    Re: Pool calculator help

    Quote Originally Posted by frustratedpoolmom
    You are using the calculator wrong, and/or don't seem to understand how to lower the TA...

    You calculate a dose of muratic acid to lower the PH to 7.2. Then you begin aerating the water. The acid will lower BOTH the Ph and the TA. The aeration will raise the PH back up to 7.6ish. Then you repeat the acid addition and aeration, noting the change in TA with each acid addition. This process can take awhile - depending on your source for aeration it can take several days. Eventually the TA will drop into range, and the aeration gets your PH where it needs to be.

    Hope this helps.
    So how am i using it wrong? My current pH is 7.2. My TA is still too high. Look at my screen shot again, the first column is my current readings. I think you answered the question and apparently the answer is that I have to just keep aerating until my pH rises and then I can resume adding acid to reduce TA?

    Correct?

    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Re: Pool calculator help

    Quote Originally Posted by Thinkly
    I think someone answered the question and apparently the answer is that I have to just keep aerating until my pH rises and then I can resume adding acid to reduce TA?

    Correct?
    Correct.

    You lower TA by adding acid. But there's a limit to how much acid you can add at once, because acid also lowers pH, and it is Very Bad to have the pH go down too far (i.e. below 7.0). The pool calc could try to predict how much acid you will (probably) need in total, but then you would be tempted to add it all at once, which is Very Bad. And Very Bad = the opposite of Trouble Free!
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    Re: Pool calculator help

    Thanks!
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    frustratedpoolmom's Avatar
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    Re: Pool calculator help

    You were using the pool calculator to calculate dosing to lower TA - I was trying to explain that you need to use it to calculate dosing to lower PH.
    Helpful links: Pool School; CYA/Chlorine Chart
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    Re: Pool calculator help

    Quote Originally Posted by frustratedpoolmom
    You were using the pool calculator to calculate dosing to lower TA - I was trying to explain that you need to use it to calculate dosing to lower PH.
    I understand now. Thanks.
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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