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Thread: FC holding, CC non-existent even with CYA

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    FC holding, CC non-existent even with CYA

    After the balancing of my water was completed a few weeks back, I've been able to hold free chlorine. I'm consistently between 2ppm and 3ppm and have been adding about 2 gallon per week.

    I brought my stabilizer up to 60ppm two weeks ago when I added chlorine. At the time, I was showing 2ppm combined chlorine. I tested the water again a few days after this and it showed 0ppm. More chlorine, waited 48 hours, tested again and it's 0ppm.

    I shock the pool, bringing total chlorine up to 10ppm. Check the next day and I have 5ppm free, 2ppm combined, 7ppm total.

    Checked a few days later and I'm back to 3ppm free, 0ppm combined. Stabilizer is still at 60ppm.

    Why can't I seem to hold combined chlorine, even with stabilizer staying consistent and free chlorine available?

    Denis
    Clearwater, Florida

    12,000 gallon kidney shaped gunite pool
    Pentair Whisperflo 3/4HP Pump
    Pentair CCP420 420sq/ft Cartridge Filter
    Pentair Intellibrite 5G 120V Pool Light

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    Mod Squad zea3's Avatar
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    Re: FC holding, CC non-existent even with CYA

    You don't want to hold CC! That is the waste chlorine produced by oxidation. Keep your FC at the upper end of your recommended level, which should be 9 ppm for your pool. FC is the active chlorine that sanitizes your pool. Check your water daily and add enough chlorine to keep the level around 9. Don't let the FC drop below 5 ppm, that is the low end of your recommended level.
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    Butterfly's Avatar
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    Re: FC holding, CC non-existent even with CYA

    What zea said. Keep the fc between 5 & 9 w/your CYA of 60.
    I suggest you should do an overnight FC loss test to rule out organics.

    I shock the pool, bringing total chlorine up to 10ppm.
    Shock level for CYA of 60 is somewhere between 18 and 24.
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    Re: FC holding, CC non-existent even with CYA

    Quote Originally Posted by zea3
    Don't let the FC drop below 5 ppm, that is the low end of your recommended level.
    That much? I was always aiming for 3-4 ppm. The pool store barked at me when they tested me at 5ppm, saying that was "really dangerously high".
    Clearwater, Florida

    12,000 gallon kidney shaped gunite pool
    Pentair Whisperflo 3/4HP Pump
    Pentair CCP420 420sq/ft Cartridge Filter
    Pentair Intellibrite 5G 120V Pool Light

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    Mod Squad Bama Rambler's Avatar
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    Re: FC holding, CC non-existent even with CYA

    Denis, you've been around here long enough to know that pool stores don't take into account the effect CYA has on the FC level.
    You should always go by the chlorine/cya chart for your FC level regardless what the PS barks about!
    Dave J. TFP Moderator
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    Melt In The Sun's Avatar
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    Re: FC holding, CC non-existent even with CYA

    If they bark at you again, just bring your python in next time!
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