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Thread: Lowering TA - Do I have to go to 7.0-7.2?

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    Join Date
    Mar 2015
    Harvey, LA

    Lowering TA - Do I have to go to 7.0-7.2?

    Right now my TA is right around 120 (starts turning red at 11 drops, doesn't change anymore after 12), so I think I'd like to play around with lowering it a bit (I say playing because pool re-plastering is coming in the next couple of weeks, but I want to get the feel for adjusting these things while it doesn't matter as much). I understand the noted way to do this is to lower to 7.0-7.2 and aerate, but do I really have to go that low, or is that just the most efficient level to go to? I was at 7.8 a few days ago and added some MA to lower it to 7.5, and wondering if bouncing between 7.8 and 7.5 will have the same effect, or if there's something special about getting closer to 7.0 here...
    17.4k gallon IG pool with attached spa (spa itself is 730gal), Super Blue Diamondbrite plaster, Circupool SI-45+ SWG, BH/Hayward Cartridge Filter, 2hp 2speed Hayward Super II pump, , Jandy Valves, Waterway Skimmers, Rheem 400k Heater, Polaris 360 cleaner, built 2000+-, replastered June 2015, TF-100 kit---Here's my pool test reading history

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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Lowering TA - Do I have to go to 7.0-7.2?

    It is more efficient if you go lower for the pH. Partly because the pH will rise faster in the lower 7s than in the upper 7s.

    You can keep it between 7.5 and 7.8, but the pH will not rise as fast meaning you will not get to add acid as fast.
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    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: Lowering TA - Do I have to go to 7.0-7.2?

    The form of the carbonate in the water varies with pH. Mostly carbonic acid below about pH 6.3, mostly bicarbonate between 6.3 and 10.3, and mostly carbonate above 10.3. Alkalinity is lowered by having the carbonate in the form of carbonic acid or dissolved carbon dioxide and then aerating to get it out of the water. There is almost no carbon dioxide in the water at pH 8, and there really isn't very much at pH 7, but that's about as low as you can go without risking damage to the pool.

    Bottom line is that the process is orders of magnitude faster at 7 than it is at 7.8.
    TFP Moderator
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