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Thread: Alkalinity Level with Auto Pool Cover

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    Join Date
    Jul 2011
    Location
    St. Paul, MN
    Posts
    244

    Alkalinity Level with Auto Pool Cover

    For those of you with auto pool covers where your pool is covered the majority of the time, what TA level do you find you need to keep pH stable? Before my auto cover, a TA of 90 would give stable pH. With the auto cover, I find I need my TA to be 120-130. I understand that with the cover on there is less CO2 outgassing. Just curious if others have observed the same phenomenon.
    20'x40' Oval 27,000 gallon Vinyl IG, Coverstar Auto Cover
    Hayward MaxFlo SP2303VSP, Sta-Rite PLD50 30 sq. ft. DE filter
    Rheem 266,000 btu natural gas heater
    Dolphin Nautilus Plus with Clever Clean
    TF-100 testkit w/ Speed Stir

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    Join Date
    Feb 2015
    Location
    Santa Cruz, CA
    Posts
    409

    Re: Alkalinity Level with Auto Pool Cover

    My TA is always about 90 - it hasn't moved much no matter what I do. Our fill water is high TA (150 I think?), and we only have 2 therapy jets on one wall that could help us lower the TA...

    I end up putting in around 16oz of Kemtek 14.5% acid each week, so haven't tried to lower the TA to say 70...
    2015 Build Link: 15'x30' Rectangle (3'-6", 5', 4' depth) 14,000 Gallon Pool, Finish: Wet Edge Primera Stone Black Kona. TF-100 Test Kit, Dolphin DX5+S Robot, Jandy CL460 Filter, VS 2HP pump, AquaPure 1400 SWG, iAqualink2, Automatic Safety Cover. No Heater

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    Join Date
    Oct 2013
    Location
    Iowa
    Posts
    89

    Re: Alkalinity Level with Auto Pool Cover

    When just using bleach our manually chlorinated auto-covered pool seems to be pH stable regardless of TA level. I've had it as low as 90, and currently it is at 200 (It's been a crazy opening this year). When we first moved in I was letting the TA drift down to TFP recommended range, but then before we went on vacation I added trichlor pucks to the feeder to see how that worked and was surprised to see my pH drop like a rock. Since then I keep the TA higher in the 120-140 range since we don't ever seem to have any pH drift, which I understand is the only reason to keep it low.

    In 3 years, I've only once added acid, and that was when we first moved in after replacing 3/4 of the water to lower CYA. With the exception of this spring opening, I only add soda ash when using trichlor, by keeping the TA higher I don't have to add soda ash as often when using it.
    20,000gal in-ground 16x36 sentry pools vinyl liner, Pentair sand filter, Pentair minimax NT heater, auto-cover, Polaris 280 cleaner.

  4. Back To Top    #4

    Join Date
    Jul 2011
    Location
    St. Paul, MN
    Posts
    244

    Re: Alkalinity Level with Auto Pool Cover

    Quote Originally Posted by dfahrion View Post
    When just using bleach our manually chlorinated auto-covered pool seems to be pH stable regardless of TA level.
    That seems to be somewhat similar to what I am experiencing. When my TA is around 90, my pH wants to be stable at 7.2-7.3. If I add borax to get it to 7.6, it will slowly drift back down to 7.3.

    This year my TA is around 130 (because I had to add some tap water this spring) and my pH is holding steady closer to 7.5.
    20'x40' Oval 27,000 gallon Vinyl IG, Coverstar Auto Cover
    Hayward MaxFlo SP2303VSP, Sta-Rite PLD50 30 sq. ft. DE filter
    Rheem 266,000 btu natural gas heater
    Dolphin Nautilus Plus with Clever Clean
    TF-100 testkit w/ Speed Stir

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