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Thread: High pH - Normal?

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    Question High pH - Normal?

    Seems like whenever I check the pH level in my spa each week I notice that the pH level is 8.2 ppm. With a target of 7.4 ppm, I naturally add the appropriate amount of acid. The next time I check the pH it's back up to 8.2 ppm. Is this normal?

    I might add: (1) the spa is covered, (2) it is rarely used this time of year, (3) water temp = 57 - 65F. All other chemistry levels are on target.

    Thank you kindly.

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    JoyfulNoise's Avatar
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    Re: High pH - Normal?

    What's your TA?

    pH rise is completely dominated by the CO2 outgassing that comes from the aeration in the tub. TA is a direct measure if your carbonate alkalinity. If your TA is too high, pH rise (or acid demand) will always be present.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: High pH - Normal?

    Quote Originally Posted by JoyfulNoise View Post
    What's your TA?

    pH rise is completely dominated by the CO2 outgassing that comes from the aeration in the tub. TA is a direct measure if your carbonate alkalinity. If your TA is too high, pH rise (or acid demand) will always be present.


    Sent from my iPhone using Tapatalk
    Matt: TA = 80ppm. And since the spa is rarely used this time of year, the only aeration comes from the daily 2-hour filtration cycle (about 1200 rpms).

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    JoyfulNoise's Avatar
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    Re: High pH - Normal?

    We typically recommend keeping the hot tub TA down at 50ppm just for this very reason. Even just a few cycles are enough to drive up pH. You can also add 50ppm borates to your spa water to help control pH rise.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: High pH - Normal?

    Matt: Does the target TA of 50ppm apply for a 2,360 gallon, in-ground SW spa like mine? If so, is there a preference of either lowering the TA to 50ppm or adding 50ppm of borates to control pH rise? Thank you!

    Kit
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    JoyfulNoise's Avatar
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    Re: High pH - Normal?

    You could get a bubble cover for the pool. If you fit it snug to the walls it will arrest most of the CO2 outgassing and hold down the pH rise.

    If you pH rise is as fast as you describe (0.5+ pH units in 24 hours), then borates will barely make a dent.

    Is this swim spa newly plastered?


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: High pH - Normal?

    The spa is always covered with an auto cover (which is always in place except when in use). No, the spa was plastered one year ago.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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    JoyfulNoise's Avatar
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    High pH - Normal?

    Try to lower your TA to 60ppm. See what impact that has on your acid demand. The auto cover should be sufficient as they typically ride on the water surface a bit for buoyancy.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: High pH - Normal?

    Thank you, Matt. I will give it a try.
    Kit
    14' X 11' rectangular in-ground spa; 2,360 gals; plaster/gunite; SWCG (Pentair IntelliChlor); Pentair Intelliflo varaible-speed pump; EasyTouch4 control system; cartridge filters; auto cover

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