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Thread: Adjusting CSI with temperature?

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    matj6876's Avatar
    Join Date
    Jul 2007
    DFW, TX

    Adjusting CSI with temperature?

    Trying to stay half a step ahead of the game; I was wondering what to do as the pool cools off this fall and winter.
    I'm in TX so I'm not going to close it but have noticed that as the pool temp falls my balanced numbers now:
    pH 7.5
    FC 5
    CC 0
    TC 5
    TA 90
    CH 340
    CYA 40-50
    Salt 4400
    Temp 86F
    CSI -0.17 ("balanced")

    ...become more and more (potentially) corrosive, or negative.

    I know that CSI is affected by many factors but it would seem that pH, in this instance plays the biggest part.
    Is the solution to this, low temp, potentially corrosive CSI just to let my pH drift up (as it naturally does - SWCG!!) to around 7.9, as opposed to 7.5 as the temp falls? Or am I over simplifying things?

    Thanks again in advance.
    My Pool: 27K gal IG plaster, IntelliFlo i1 pump, Pentair FNS Plus DE Filter, Intellichlor IC40 SWCG, Polaris 3900 Pressure Side Cleaner

  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA
    The good news is that you normally don't have to worry about the variation in the CSI with temperature because as the temperature falls, the pH goes up on its own keeping the CSI more stable (it drops only a small amount). For example, at standard parameters of pH 7.5, TA 100, CYA 30, a drop in temperature from 85F to 55F causes the pH to rise to 7.7 so the CSI drops from +0.07 to -0.01 which isn't very much.

    So I wouldn't worry about it -- you should not need to adjust your pH at all, or if you realy wanted to you wouldn't do so by more than about +0.1

    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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