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Thread: Calcium Hardness and soda ash

  1. #1
    Senior Member
    Join Date
    Jul 2008
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    Seacoast, NH
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    Calcium Hardness and soda ash

    I added 4 lbs of CH. My pH is 7.2 and I want to add some borax, which are at 30. The CH label says not to add pH plus the same day as the CH. Is that true? If it is, does it apply to borates too?
    19,000 gallons
    Cartridge filter
    IG vinyl, Propane heater
    SWG, 2006 Taylor Test Kit

  2. #2
    Administrator JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Calcium Hardness and soda ash

    Yes, it applies. You don't want to add calcium and also raise the PH on the same day. It isn't such a big deal if you are well below the minimum CH level for a plaster pool (i.e. well below 250) and not planning to go above that right now, but gets to be rather important if CH is in the normal plaster range, and crucial when CH is above 400.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. #3
    Senior Member
    Join Date
    Jul 2008
    Location
    Seacoast, NH
    Posts
    134

    Re: Calcium Hardness and soda ash

    My CH is 125. I've never worried about it being low because I have a vinyl pool, but I was reading my SWG manual last night and it says the CH should be 200-400 so I decided to raise it.
    19,000 gallons
    Cartridge filter
    IG vinyl, Propane heater
    SWG, 2006 Taylor Test Kit

  4. #4
    Administrator JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    35,078

    Re: Calcium Hardness and soda ash

    Don't bother. CH above 100 in a vinyl liner pool serves no purpose except to enrich the chemical company. (And below 100 is fine in all but the most unusual situations.)

    It you are bound and determined to raise CH, don't go over 200 on the same day as anything that raises PH.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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