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Thread: Total chlorine

  1. Back To Top    #1

    Join Date
    Aug 2016
    Houston, TX

    Re: Chlorine/CYA relationship

    I realize this is an old thread, but it came closest to what I am searching for so I will resurrect. After reading chem geek's post about active vs. bound (to CYA) chlorine levels here, I was curious what our test kits are measuring. When I get a reading of that TOTAL (bound and unbound) or just the unbound/active level? Since I haven't come across any debate about this, I assume it is the total...but wanted to confirm since I did not know if the reagent would react to "bound" chlorine or not.
    13.5k gallon IG gunite
    200sf Pentair C&C cartridge
    Pentair SuperFlo 1.5HP
    Rainbow 320 using Trichlor
    Built in 1999, re-plastered and re-coped in 2013

  2. Back To Top    #2
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Tucson, AZ

    Re: Total chlorine

    The DPD-FAS test measures both free chlorine (FC) and then combined chlorine (CC). Free chlorine is made up of three components - hypochlorous acid (HOCl), hypochlorite anion (OCl-) and chlorine bound to CYA (HCy-Cl). HOCl/OCl- are considered active chlorine and the HCy-Cl is bound or reserve chlorine. So when you measure FC with your DPD-FAS test, you are measuring all of the active and reserve chlorine in the water.
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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