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Thread: Timeframe for lowering TA and letting pH rebound?

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    Join Date
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    Timeframe for lowering TA and letting pH rebound?

    Getting ready for boric acid add. Pool calc said that I needed to add 3/4 gallon MA to lower pH from 7.8 to 7.2 or so while lowering TA from 90 to 60. Have spa overflow that I believve serves as a good aerator. About how long should it take for TA to reduce and pH to rebound? Boric Acid coming tomorrow and would like to dump it tomorrow night or Saturday morning if possible. Will be testing of course but about how long should I anticipate?
    2006 IG 18.6K gal marcite saltwater w/integrated 800 gal spa, spillover, 2 Main and 2 Spa Drains, 2 Skimmers
    Goldline Aqua Logic PS-8, Aqua Pod Remote, Hayward GLX-Cell-15-W SWG, Hayward Pool Vac XL, Cartridge filter, single speed pump
    Taylor K-2006, Lamotte Borate Strips

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    Mod Squad Jimrahbe's Avatar
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    Re: Timeframe for lowering TA and letting pH rebound?

    first,

    It takes me a day, or maybe two, depending on when I start, to reduce my TA from 120 to 60 or so. But this is not a one time deal. You have to do it every three or four hours until you get where you want to be. So, just as an example, not real numbers... If you add 3/4 of a gallon of MA, and it brings your pH down to 7.2, TA may only drop to 83. (I drop my pH to 7.0).. In about three or four hours pH will be back to 7.4, so you need to add more MA to drop it back to 7.2/7.0 which will drop the TA to say 75... etc. You have to keep this cycle up until you get the TA where you want it.

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Calder Spa.

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    Re: Timeframe for lowering TA and letting pH rebound?

    Quote Originally Posted by Jimrahbe View Post
    first,

    It takes me a day, or maybe two, depending on when I start, to reduce my TA from 120 to 60 or so. But this is not a one time deal. You have to do it every three or four hours until you get where you want to be. So, just as an example, not real numbers... If you add 3/4 of a gallon of MA, and it brings your pH down to 7.2, TA may only drop to 83. (I drop my pH to 7.0).. In about three or four hours pH will be back to 7.4, so you need to add more MA to drop it back to 7.2/7.0 which will drop the TA to say 75... etc. You have to keep this cycle up until you get the TA where you want it.

    Jim R.
    Thanks Jim. I appreciate you sharing your experience. I will check it later tonight after 5-6 hours and see what is up and then again in the morning or whenever. Go back and forth as you say until it stabilizes. Good to know that it is hours not days...I guess that is what I was questioning.
    2006 IG 18.6K gal marcite saltwater w/integrated 800 gal spa, spillover, 2 Main and 2 Spa Drains, 2 Skimmers
    Goldline Aqua Logic PS-8, Aqua Pod Remote, Hayward GLX-Cell-15-W SWG, Hayward Pool Vac XL, Cartridge filter, single speed pump
    Taylor K-2006, Lamotte Borate Strips

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    Re: Timeframe for lowering TA and letting pH rebound?

    It takes way longer if you wait for it to go all the way back up to 7.8. The pH rise from 7.2 (or 7.0) to 7.5 is much faster than the rise from 7.5 to 7.8. You can save your time by re-dosing the acid when it gets to 7.4/7.5.
    John - 16,000 gallon | in ground | pebble | Triton II sand filter | TF100 | speedstir | Hayward Phoenix 2x

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    Re: Timeframe for lowering TA and letting pH rebound?

    Moved post to my other thread.
    2006 IG 18.6K gal marcite saltwater w/integrated 800 gal spa, spillover, 2 Main and 2 Spa Drains, 2 Skimmers
    Goldline Aqua Logic PS-8, Aqua Pod Remote, Hayward GLX-Cell-15-W SWG, Hayward Pool Vac XL, Cartridge filter, single speed pump
    Taylor K-2006, Lamotte Borate Strips

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