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Thread: Calcium Carbonate Precipitation Potential using PoolEquation

  1. Back To Top    #1

    Join Date
    Aug 2008

    Calcium Carbonate Precipitation Potential using PoolEquation

    Using the "PoolEquations" Excel spreadsheet I am trying to determine what would the "Calcium Carbonate Precipitation Potential" be if the numbers looked as follows:

    Cl 5
    pH 7.3
    TA 120
    CH 475
    CyA 80
    Salt 3200
    Borates 50
    Orthophosphates 2000 (ppb)
    Temp at present 78F (to max 84F and an average of 81F)
    Carbonate Alkalinity (ppm CaCO3) 92.0
    CSI -0.18
    LSI -0.09

    Is the "Calcium Carbonate Precipitation Potential" number OK or should one or more of the above be adjusted, and if so to what figure(s)?

    Thank you.
    10,000 gal plaster pool,3/4 hp WhisperFlo pump, Sta-Rite Great White GW9500 pool cleaner, Hayward 300 lb Sand Filter
    Use Magenta Stuff for Iron and Silica control.
    Balance: pH 7.7 Cl 7 -8 Alk 70-80 CH 325 CyA 30 in winter - 50 in summer NaCl 1010 TDS 1200

  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Calcium Carbonate Precipitation Potential using PoolEqua

    I used 3734 ppm TDS to get the salt level at 3200 ppm. The rest of the TDS is calcium, bicarbonate and boric acid. I get a CSI of -0.21 so basically similar to your number. If I click on the Calculate CCPP button I get a CCPP of -11.2

    The Calcium Carbonate Precipitation Potential (CCPP) is normally used when the CSI is positive to determine how much calcium carbonate can potentially precipitate. As it precipitates, the pH and the CH drop so accelerate stopping this precipitation. It's essentially a measure of capacity. It is not a measure of rate.

    When the CSI is negative, the CCPP tells you how much calcium carbonate can dissolve (say, from plaster) before such dissolving stops. So I don't think it's very useful to look at when the CSI is negative, especially when the CSI is only a little negative. At any rate, it just says that your CSI isn't so negative as to cause problems with plaster, but you already knew that from the CSI number itself.
    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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