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Thread: CSI too high?

  1. Back To Top    #1

    Join Date
    May 2014

    CSI too high?


    Using TFP method this year, first time, great results - sparkling clear, no algae, no shocking...easy. (Except for disposing of the empty liquid chlorine jugs.)

    But my question is around Calcium Saturation Index. Poolmath is giving me +.41 and I'm getting concerned about damaging the plaster which is already kind of rough.

    Using TF100 test kit:
    FC: 4.0
    CC: 0
    CH: 400
    TA: 100
    PH: 7.8
    CYA: 50

    I feel like I should get the PH down to 7.4-ish.
    I've put in enough dry acid to do so, but the PH only went down to 7.6, and then back up to 7.8 within a week.
    BTW I've owned the pool for two years - there appears to be some calcium scaling through-out the pool (patchy/streaky areas) but it hasn't changed over the past two years (brushing doesn't seem to help.)

    Should I be concerned?
    Should I try to overshoot the PH down to 7.something?
    Should I drain and refill to lower CH? (Expensive - local tap water CH measures 200, so I'd have to truck in water.)

    Thanks a lot for any comments!

    30k gallon inground gunite, Pentair Intelliflo VS pump, Sta-Rite System 3 Catridge Filter, 2 main drains, 2 skimmers, 4 wall returns, 2 floor returns, 2 Jandy valves, 2 underwater lights (hey, I didn't design this thing...), LoopLoc safety cover for the winter, average chlorine usage over 3 years: 1.2ppm/day, using 12.5% sodium hypochlorite ($3/gal) and following TFP PoolMath directions. Works great!

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: CSI too high?

    Plug all your numbers into poolmath in the Now and Target columns. Then go play with the different variables. You'll be surprised to fin out how little effect CH actually has on CSI, and how much temperature has. You'll also see how lowering pH and/or TA can easily drive that number deep into negative territory. They are the critical numbers, really.

    The simplest thing to do is to lower pH to 7.2. This will also lower TA. Plug your numbers in and then go waaaay down to Effects of Adding Chemicals and see just how much TA will drop by the addition of whatever acid you need to lower pH. Just keep knocking pH back to 7.2 whenever it starts to approach 7.8 and the TA will lower substantially and the CSI will shift more to neutral.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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