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Thread: freezing point of a SW pool

  1. #1
    Senior Member
    Join Date
    Jul 2008
    Location
    Solon, Iowa
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    170

    freezing point of a SW pool

    Does anyone know how 3000 ppm salt affects the freezing point of water? I'm guessing it will a little, but not enough to matter to a typical Iowa winter.

    Kelly
    15X30 AGP, Lomart beaded liner;
    1.5 HP Sta-Rite pump with 21 inch sand filter (Zeobrite media)
    Mineral Springs (Aquatrol) SWCG, Rigid PVC plumbing, 2 inch
    Four 4X12 Techno-Solis solar panels, rack mounted, Goldline Solar Controller

  2. #2
    Senior Member
    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    8,315

    Re: freezing point of a SW pool

    The amount of salt in an SWG pool has a negligible effect on the freezing point of water.

    The formula is that the freezing point depression for water, in Celsius, is 1.86 times the molality of dissolved substance. 3000 ppm salt in water is around 0.05 moles/liter which is essentially the same as molality (moles/kg) since the density doesn't change much. You double this concentration since sodium and chloride ions are separate so around 0.1 * 1.86 = 0.186C = 0.3F so not even one degree improvement.

    Richard
    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"

  3. #3
    Senior Member
    Join Date
    Jul 2008
    Location
    Solon, Iowa
    Posts
    170

    Re: freezing point of a SW pool

    Thanks. That's less than I figured, and I was figuring small!
    15X30 AGP, Lomart beaded liner;
    1.5 HP Sta-Rite pump with 21 inch sand filter (Zeobrite media)
    Mineral Springs (Aquatrol) SWCG, Rigid PVC plumbing, 2 inch
    Four 4X12 Techno-Solis solar panels, rack mounted, Goldline Solar Controller

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