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Thread: Question about lowering PH

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    Woodberg's Avatar
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    Question about lowering PH

    Current numbers;
    FC - 2.5
    CC - 0
    PH - 7.9
    TA - 110
    CH - 280
    CYA - 40

    These were my test results this morning. My pool is only a few months old, so I have been using Trichlor pucks as my main chlorine source while the CYA was rising. I'm thinking its about time to stop doing that. Based on the above numbers I added 104 oz of bleach to get my FC up to 5.

    My question is what to do with the PH and TA.

    From looking at the pool calculator, if I switch to using bleach, then I need to lower my TA to 70-90. Obviously my PH is a little high and also needs to be lowered. Based on the Pool calculator, I need to add about 18oz of Muriatic acid to lower my PH to 7.6. I think I read that adding acid will also lower the TA, but by how much?

    I have a SPA that overflows most of the day so I get a decent amount of aeration. I think this is part of the reason why my PH continues to rise.
    20,000 gallon gunite pool, attached spa, Pebblesheen finish, Paramount PCC-2000 infloor cleaning system, Paramount ClearO3 ozone system, Intelliflo VS main pump, Whisperflo 1HP cleaner pump, StaRite cartridge filter, StaRite heater

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    Re: Question about lowering PH

    just add some acid to lower your pH...you may want to keep you FC a little higher...the other numbers are fine for now...
    25,000 gal IG Utopia pool/Raypack gas heater/BBB

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    Re: Question about lowering PH

    ideliver has got you covered. When you add the calculated amount of acid, your TA will drop along with it your pH. Then, unless you have other issues down the road (rapidly rising pH), just leave your TA alone.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Woodberg's Avatar
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    Re: Question about lowering PH

    How long does it take for the acid to take effect? I checked after 1 hour and the FC level had risen to 5, but the PH, didn't look like it had changed much.

    Is there a way to know how much the TA will drop when adding acid?
    20,000 gallon gunite pool, attached spa, Pebblesheen finish, Paramount PCC-2000 infloor cleaning system, Paramount ClearO3 ozone system, Intelliflo VS main pump, Whisperflo 1HP cleaner pump, StaRite cartridge filter, StaRite heater

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    Re: Question about lowering PH

    Quote Originally Posted by Woodberg
    How long does it take for the acid to take effect? I checked after 1 hour and the FC level had risen to 5, but the PH, didn't look like it had changed much. You might give it another hour but I suspect you'll need to add more.....mine usually changes in 30 minutes.

    Is there a way to know how much the TA will drop when adding acid? No, I don't think so. Even the pH change is a little inexact but you'll stay well within acceptable parameters
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Question about lowering PH

    The amount of change in TA from the amount of acid needed to lower you pH from 7.9 to 7.6 is going to be less than the precision of the TA test!
    If you want to lower your TA a bit I would suggest that when you add acid to lower the pH lower it ot 7.0. It will rise on its own over time and each time you do this you will take a bite out of your TA. Once your TA is at target then only add enough acid to lower the pH to normal levels when it rises too high.

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    JasonLion's Avatar
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    Re: Question about lowering PH

    Quote Originally Posted by Woodberg
    Is there a way to know how much the TA will drop when adding acid?
    Yes, my Pool Calculator can tell you that. Take a look at the effects of adding chemicals section down near the bottom. The PH calculations in that section are very approximate, but the TA calculations are quite accurate.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Woodberg's Avatar
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    Re: Question about lowering PH

    Thanks, that worked great.
    20,000 gallon gunite pool, attached spa, Pebblesheen finish, Paramount PCC-2000 infloor cleaning system, Paramount ClearO3 ozone system, Intelliflo VS main pump, Whisperflo 1HP cleaner pump, StaRite cartridge filter, StaRite heater

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