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Thread: FC (free Chlorine)

  1. Back To Top    #1

    Join Date
    Mar 2014
    Scottsdale, AZ

    FC (free Chlorine)


    First time on the site. So far I find it very informative. Can you tell me what it means if my suggested FC level on the Pool math calculator says 4 to 6. Does this means 4 to 6 ppm's. If so, that seems very high compared to what my Taylor test kit suggests. Can someone help me clarify this? Thanks.

  2. Back To Top    #2
    Casey's Avatar
    Join Date
    Apr 2007
    SW PA

    Re: FC (free Chlorine)

    Welcome to TFP.

    It means PPM. Your FC works with your CYA/Stabilizer levels. You can read about that in here Pool School. I would suggest ABC's of Pool Water Chemistry and Recommended Levels.
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: FC (free Chlorine)

    Welcome to TFP!

    Yes, 4 to 6 means 4 ppm to 6 ppm.

    Most sites/products continue to repeat FC level recommendations from before CYA was discovered/understood. Without CYA it is very important to keep FC fairly low. But once there is CYA in the water everything changes dramatically. CYA binds to chlorine and makes much of it inactive/held in reserve. To maintain active chlorine levels that are high enough you need to have a higher FC level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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