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Thread: How To Reach Breakpoint Chlorination With CYA at 75 ppm

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    How To Reach Breakpoint Chlorination With CYA at 75 ppm

    I want to remove 0.5 ppm of CC. The formula, CC x 10 = ppm of FC to add to reach breakpoint, is clear enough. However, because of the presence of 75 ppm of CYA in a 20K, SWG, IG pool, should more than CC x 10 = ppm of FC be added to overcome the CYA? And, if so, should that additional FC be 40% of the CYA?

    I am going to be using 12.5% sodium hypochlorite.

    Thanks
    19.5K, 18'x40', oval, IG, pebble, saltwater pool
    Jandy, 48 sf., DE filter (using Zeo Fiber instead of DE)
    Jandy, PLC 1400, SWG
    Zodiac, 1HP, single speed pump

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    JasonLion's Avatar
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    The entire breakpoint chlorination story is a myth, not true at all.

    Given how little CC you are dealing with all you probably have to do is raise the FC level up to the high end of the normal range, or if that doesn't work right away, shock level will be fine.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    Thank you for the quick reply

    When you say shock level do you mean the suggested FC level from the pool calculator (20 ppm) or do you mean the FC level from the Chlorine/CYA Chart
    (28 ppm)?

    Thanks
    19.5K, 18'x40', oval, IG, pebble, saltwater pool
    Jandy, 48 sf., DE filter (using Zeo Fiber instead of DE)
    Jandy, PLC 1400, SWG
    Zodiac, 1HP, single speed pump

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    Smykowski's Avatar
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    They are slight variations on the same formula, so if you shoot for the midpoint, you're fine.

    The chart in pool school is a little more aggressive, but when you're talking about numbers that high, they'll both work.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    Wanted to report on the results of this topic: Sunday night I began the shocking process following the advice I received at this site, i.e. I added (very quickly) 3.9 gal. of liquid bleach, 12.5%, which is approx. 24 ppm for my SWG pool. At that time, CYA was 60 ppm. My purpose was to remove 0.5 ppm of CC, as well as to correct any previous mistakes I may have made, and to make up for what I concidered a VERY POOR, paid for, "professional" pool opening.

    Here are the results as of this writing:

    Water Clarity: Crystal clear
    FC: 9 ppm
    CC: 0.00
    ph: 7.5
    Temp: 82
    TA: 100 ppm
    CH: 200 ppm
    CYA: 60 ppm

    I hope this post helps and sets some minds at ease, i.e. adding that much bleach seems like a lot, but it works! Also, all testing was done with a TF-100 test kit and a Taylor 2005 test kit.
    19.5K, 18'x40', oval, IG, pebble, saltwater pool
    Jandy, 48 sf., DE filter (using Zeo Fiber instead of DE)
    Jandy, PLC 1400, SWG
    Zodiac, 1HP, single speed pump

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    Join Date
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    What is the need to get rid of 0.5 CC? I thought that was considered a normal level. I occasionally have 0.5 CC but the next time I check it's always 0.0.
    23x40 freeform w/spa, 28,000 gal. PCC-2000 in-floor cleaning. Pebble Sheen w/flagstone coping. 14' weeping wall, (2) 18" sheer descents. Sta Rite- cart 400 sqft. filter, Intellipro VS pump, 1hp (cleaning)2hp (water feature)Max E Pro's. Easy Touch 8 function w/IPod. Rainbow chlorinator, Paramount Clear O3 (I know, I know), Max-E-Therm 400K heater.

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    Richard320's Avatar
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    Quote Originally Posted by Bluechip
    What is the need to get rid of 0.5 CC? I thought that was considered a normal level. I occasionally have 0.5 CC but the next time I check it's always 0.0.
    It's just the novelty of his new Junior Scientist playset. Let him have his fun

    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    duraleigh's Avatar
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    Re: How To Reach Breakpoint Chlorination With CYA at 75 ppm

    Confirming what Bluechip and Richard320 are saying, .5 ppm CC and 0 ppm CC are exactly the same thing for our purposes.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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