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Thread: Fill water and chemistry

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    Fill water and chemistry

    I just measured my fill water, straight from the tap and after sitting for 24 hours. I know that straight from the tap will have a lower pH than later after the dissolved CO2 is released as the water goes from water main pressures to atmospheric pressure.
    FC 0
    TA 220
    CH 20
    pH 7.9 from tap
    pH 8.4 maybe after 24 hours, hard to be sure color was above my testing kit max at 8.2, guessing at 8.4

    I notice that when I put these values into the Pool Calculator, using pH of 8.4, that the CSI = 0 exactly.

    Is this some sort of universal truth or just a coincidence? At rest, water will balance out the pH to make CSI= 0 at a given TA and CH? Just wondering..... and wondering what that says for chemistry post resurfacing the pool.

    Chemistry is not my long suit and so while I think about it and try to understand, I need to have simple explanations and pictures to make it make sense to me.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Fill water and chemistry

    The CSI coming out at zero is just coincidence. CSI starts negative, and with TA that high the PH will continue to go up until CSI is positive. Most places the tap water has strongly negative CSI. Your high TA tap water just happens to bring you into the range where you will cross over into positive CSI if you let it sit out.
    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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