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Thread: Saturation Index (sci) Question

  1. Back To Top    #1

    Join Date
    Sep 2015
    Scottsdale Arizona

    Saturation Index (sci) Question

    Does it matter if csi is -.5 or -.2 or 0.0 with a high CH of 550ppm I think it is better with a slight negative value to keep calcium from forming on pool surfaces, true or false? Pool math
    States -.6 to +.6 is satisfactory.
    TF-1000 test kit. Using Liq. Chlorine and pool math.
    FC 12
    TC 12
    CC 0
    TA. 80
    CYA 80 to 90
    PH 7.5
    CH 550
    Water temp 48F

    15,000 gal in ground pebble tech pool
    Triton 100HD 4.91sq. ft. filter area sand filter
    Challenger High flow 2HP pump/motor
    Last edited by Andy D; 12-30-2015 at 10:15 PM. Reason: Forgot something

  2. Back To Top    #2
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Tucson, AZ

    Re: Saturation Index (sci) Question

    It is preferable to keep your CSI between -0.3 and +0.3. Outside those limits there is the potential for corrosion or scale but no one can easily predict the rates.

    Looking at your numbers, your pH is really too low for a winter pool. Why are you keeping it at 7.5? In the winter, you can easily allow your pH to drift up to 7.8 and it will probably stay there for quite a while. Right now, with a pH of 7.5, your CSI is -0.32. If you let it rise to 7.8, your CSI would be -0.04. You'll have fewer acid additions if you let your pH rise a little higher.
    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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