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Thread: FC testing question

  1. Back To Top    #1

    Join Date
    Jul 2015
    Tampa, Florida

    FC testing question

    I have now been testing my own water for about a month -- what a difference! I always thought my water was really clear while I was trusting the pool store -- but now it is even clearer, and I have not had to buy any extra chemicals -- just bleach/chlorine!

    I do have a question about the different FC tests in the TF-100 kit, especially in relation to the CYA levels. When I started the process I was using the tablets, so my CYA levels were pretty high (85ppm in the first test.) Mother nature helped out here in the Tampa area and has dumped MANY inches (probably feet at this point) of rain, so I think I have replaced a major portion of my water without spending a dime. This has caused my CYA levels to come down to 60 ppm.

    The question I have has been almost answered in other places on the forum but not exactly, (or at least I can't find the exact answer) and is this: do you have to use the drop FAS/DPD test to test chlorine daily in order to test for and sustain FC levels high enough for the high CYA levels (9 FC for 80 CYA according to the chart)?

    This is what I have done, but now that the CYA levels are coming down to better levels, I think I can switch to the OT kit for the daily levels. I am already able to predict pretty accurately the amount of added chlorine needed each day based on bather load, but the massive amounts of rain we have had have made it difficult some days.

    Thanks for the help already given and for any answers to this!
    15000 gallon IG marcite; Sta-rite PXC75 w/ 75 sq. ft. cartridge filter; Pentair 3/4 hp pump; no idea what age the pool is (we've been in the house for almost 2 years); used to have a heater which we removed as it did not work; tf-100 test kit.

  2. Back To Top    #2
    Divin Dave's Avatar
    Join Date
    Oct 2013
    Longview, Texas

    Re: FC testing question

    Hi Michael,
    now that your CYA is down to 60, your minimum FC is 5 which is as high as the OT kit can measure.

    I think now that you know about how your pool consumes chlorine, you can use the OT test, just keep your chlorine above the 5 level.
    this is what a lot of us that has been around a while now do, and only use the FAS DPD about once a week.

    Hope this helps,
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge. Experience- it's what's learned just after you needed it most !!

  3. Back To Top    #3

    Join Date
    Jul 2012
    Central Texas

    Re: FC testing question

    I still use the FAS DPD all the time jaguar because I like the 'exactness' of it vs. the ranges. I typically do pH and chlorine every other day. I'm generally spot on to my predictions but it like the double check.
    Central TX / 12K GAL / IG / SWG / DE filter / Pentair SVRS & 3 swim jet pumps / Spa bench and jets / Single body of water / No heater.

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