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Thread: FC tripled in one day

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    Join Date
    May 2014
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    Dallas, Tx
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    FC tripled in one day

    Good morning. Been trouble free since April and have never enjoyed our pool more than this year. Thanks to all who helped in the transition. Yesterday my readings were:

    FC - 4.0
    CC - 0
    PH - 7.7
    TA - 50
    CYA - 40
    CH - 350

    I added one gallon of 8.25 bleach which is what I have been adding approx 3 times a week since the weather got colder.

    This morning the readings are:

    FC - 14.5
    CC - 0
    PH - 7.8
    TA - 50
    CYA -40
    CH - 350 I tested the FC 3 times and got the same readings. It is about 45 degrees here this morning. We keep our pool open and running year round. Using the same chemicals and leaving CYA for last based on some
    cold water info I have read on here. The water is beautiful. Any idea what might have happened and what I should do? Appreciate your help.
    Mike

    Pool is inground 20' x 40' 42000 gallon, rectangular plaster about 60 years old, replastered 2 years ago. Pentair VS Intelliflo pump, Pentair 420 Clean & Clear Plus Cartridge filter. Using K-2006 test kit.

  2. Back To Top    #2

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    Long Beach, CA
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    Re: FC tripled in one day

    Just let the chlorine come down on its own, you will not have to add any for a little while.

    My best guess is that the first test was not accurate for some reason and now the FC is a little high.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

  3. Back To Top    #3

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    duraleigh's Avatar
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    Re: FC tripled in one day

    1 gallon of 8.25% would've raised your FC by 2.0 ppm. There is no way to get more unless you add it.

    I suspect you had a math error as ping suggests.

    Are you using PoolMath?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    swoopman's Avatar
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    Re: FC tripled in one day

    Is it possible that the container you used to pull your water sample had any residual chlorine in it or that the water was not properly circulated before pulling the sample?
    TF-100 Test Kit
    22,000 gallon, 20x40 kidney-shape IG plaster pool built in 1986
    Nautilus NS-36 DE filter, Hayward Self Prime Super Pump 1HP
    Polaris Automatic Pool Cleaner, PB4-60 3/4 HP pump

  5. Back To Top    #5

    Re: FC tripled in one day

    If you accidentally used a 25 ml sample for the most recent test, that would mean that your actual fc is 5.8, which is close to the expected level based on the starting fc, pool volume, and amount of bleach added.

    If you have tabs in a feeder or skimmer or a swg or a peristaltic pump adding chlorine, then that could explain the discrepancy.

  6. Back To Top    #6

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    Re: FC tripled in one day

    Good morning. It appears that JamesW was correct. I must have used a 25 ml sample because this morning, my readings are back to normal. The embarrassing part is that I did the test 3 times and must have used the wrong sample size 3 times. My apologies for wasting everyones time and thank you for the support.
    Mike

    Pool is inground 20' x 40' 42000 gallon, rectangular plaster about 60 years old, replastered 2 years ago. Pentair VS Intelliflo pump, Pentair 420 Clean & Clear Plus Cartridge filter. Using K-2006 test kit.

  7. Back To Top    #7

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    Re: FC tripled in one day

    lol, it happens to the best of us. Don't take it too hard.

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    Richard320's Avatar
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    Re: FC tripled in one day

    Quote Originally Posted by mbeck5 View Post
    Good morning. It appears that JamesW was correct. I must have used a 25 ml sample because this morning, my readings are back to normal. The embarrassing part is that I did the test 3 times and must have used the wrong sample size 3 times. My apologies for wasting everyones time and thank you for the support.
    Just wait until you add the wrong reagent to one of the other tests and wonder why it won't change colors even after dumping half a bottle of the third reagent in...
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: FC tripled in one day

    You are all very kind. Thanks again and best wishes for a great Thanksgiving.
    Mike

    Pool is inground 20' x 40' 42000 gallon, rectangular plaster about 60 years old, replastered 2 years ago. Pentair VS Intelliflo pump, Pentair 420 Clean & Clear Plus Cartridge filter. Using K-2006 test kit.

  10. Back To Top    #10
    Divin Dave's Avatar
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    Re: FC tripled in one day

    Man.... dont worry! We have all been there. LOL! We can laugh with you and not at you!


    I'm glad you've enjoyed your pool more than ever before. This TFP isn't so bad is it?

    Happy Thanksgiving

    Quote Originally Posted by mbeck5 View Post
    Good morning. It appears that JamesW was correct. I must have used a 25 ml sample because this morning, my readings are back to normal. The embarrassing part is that I did the test 3 times and must have used the wrong sample size 3 times. My apologies for wasting everyones time and thank you for the support.
    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.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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