Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 9 of 9

Thread: FAS/DPD questions

  1. Back To Top    #1

    FAS/DPD questions

    I recently received my FAS/DPD stuff from Dave at TF test kits. Makes me never want to go back to OTO testing for chlorine

    The procedure I've been following is-

    1- 10ml sample of pool water.
    2- Add DPD powder until the sample turns pink.
    3- Add drops of R-0871 until sample turns clear. Divide drops by 2 (each drop is .5 ppm of FC) to get FC.
    4- Add 5 drops of DPD #3. If sample turns pink, CC is present.
    5- Add drops of R-0871 until sample turns clear. Each drop is .5 ppm of CC.

    So far so good

    What I'm wondering is do I have to test for FC first, or if all I want to know is if CC is present can I simply take the 10ml sample, add the 5 drops of DPD #3 and then add R-0871 to measure CC?

    Thanks

  2. Back To Top    #2

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,517
    Great question.....I don't know the answer.

    I'll be as interested to find out as you.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

    Join Date
    Jun 2007
    Location
    Charleston, SC
    Posts
    151
    This would be simple enough to test, and only cost you a few drops of reagant.

    Do the test the way the instructions say to, and then try it the other way and see if you get the same results.
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

  4. Back To Top    #4
    Wolfmarsh, that's logical, but with any luck, my CC is now gone

    If it's not after I test tonight, I'll try it.

  5. Back To Top    #5
    Guest

    Re: FAS/DPD questions

    Quote Originally Posted by Rangeball
    What I'm wondering is do I have to test for FC first, or if all I want to know is if CC is present can I simply take the 10ml sample, add the 5 drops of DPD #3 and then add R-0871 to measure CC?

    Thanks
    No, you would be testing TC then, not CC.

  6. Back To Top    #6
    Darn the bad luck...

    Is there any way to ONLY test for CC?

    Just curious.

  7. Back To Top    #7

    Join Date
    May 2007
    Location
    Houston, Texas, USA
    Posts
    148
    I asked the very same question not long ago. Got the same answer too
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
    "I know just enough to be dangerous"
    Pool Calc Ver 1.41 (Excel)

  8. Back To Top    #8
    Guest
    Quote Originally Posted by Rangeball
    Darn the bad luck...

    Is there any way to ONLY test for CC?

    Just curious.
    Yes, first add the dpd powder to the sample and add the titrant until the red color changes to colorless, do not worry about counting the drops, just add them until a drop turns it colorless. This will remove the FC from your sample. Then add 5 drops of the dpd #3 reagent and titrate but count those drops. You have just tested for only CC. (since you didn't count the drops in the first part you don't know what your FC or TC is!)

    by definition CC is the difference between the TC and FC. In FAS-DPD testing you are depleting the FC in the sample and then test the CC remaining. In DPD testing you test the FC and then the TC and subtract since you are adding the CC to the FC when you add reagent #3, giving you the TC.

  9. Back To Top    #9
    Ok, so that's a no.



    Thanks.

Posting Permissions

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