Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 3 of 3

Thread: Interpreting CH test color change

  1. Back To Top    #1

    Join Date
    May 2013
    Essex County, NJ

    Interpreting CH test color change

    Have Taylor K-2006 test kit and I think I may be interpreting the color change for the CH test incorrectly.

    For most of the tests in the kit, it's very easy to interpret the color change to get good results...
    FC - pink to clear
    TA - green to red
    Salt - yellow to salmon redish

    For me, the CH test color change is a little difficult to gauge or maybe I'm interpreting the color incorrectly. As I add R-0012 reagent, the color goes from red to purple at about 200ppm (20 drops) but I don't really get to blue though I keep adding the reagent, stopping at around 400ppm (40 drops). Should I be stopping the test when the color is purple or bluish purple OR do I continue testing until the color is literally blue??
    Pool: 25k gal, IG Vinyl, built 2008, DE, Hayward Progrid 4820 - 96 GPM 48 sq ft filter area, 1.5hp Hayward Super Pump, 3/4hp Hayward booster pump 6060, Aquarite SWG T-Cell-90 Rev 1.40, Hayward Phantom, Hayward H350 heater.
    Hot Tub: 2008 Sundance Cameo, 450 gal

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Interpreting CH test color change

    You keep droping until the color doesn't change any more and then don't count that last drop. It really doesn't matter if it's not exactly blue.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  3. Back To Top    #3

    Join Date
    Jul 2013
    Dallas, TX

    Re: Interpreting CH test color change

    The purple color means you have metal in the water ( I have the same problem ).

    From the Taylor website: ... ntentID=70

    Beware the Fading Endpoint

    Occasionally when testing calcium hardness you may get a purple endpoint instead of blue. This is called a "fading endpoint" and is due to interference from metal ions (most likely copper from algaecides, pipes, or source water). Retest, but prevent the interference by adding five or six drops of hardness reagent to the sample before adding the buffer and indicator. Then proceed as usual. Remember to count the drops of titrant added at the beginning when you calculate the total number of drops required to reach the endpoint.
    17K gallon IG Plaster. 48sqft Hayward DE filter. Stenner Pump

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts