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Thread: combined chlorine is EXACTLY .5 OK to leave unless rises?

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    combined chlorine is EXACTLY .5 OK to leave unless rises?

    just finally got levels under control after a couple weeks. (after an overfill/spill of water)

    For several days now PH is 7.5, simple chlorine test showing 2. With the detailed chlorine test from TF-100 showing 3.5 fc + .5 CC Pool is saltwater.

    Hoping the .5 is ok so we finally can get a couple weeks in swimming before summer ends?? I know it's right at the limit. If not okay, I guess the "shocking" procedure in poolschool would be needed....how long does that take usually, before you can get in and swim again?
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    Richard320's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Just bump up the FC a couple points for a couple days. If you're really worried, do the FAS-DPD test using a 25 ml sample. Then each drop will count as .2. Then you'll know for sure if you have a problem.

    What about the rest of the tests? Your FC may or may not be okay where it is, depending on the CYA level.

    Most important, how does the water look?
    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: combined chlorine is EXACTLY .5 OK to leave unless ri

    Yeah, if your water is sparkling, that's an important ingredient.

    My pool stays around .5CC as well. The forum suggests to treat .5CC the same as 0CC so, if your pool is clear and you aren't losing much chlorine overnight, you should be good to go!!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    A little cloudy, Richard. I just put 21oz bleach in to go up 2 points exactly. Will do full tests in a couple days.
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    Richard320's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Quote Originally Posted by filb
    A little cloudy, Richard. I just put 21oz bleach in to go up 2 points exactly. Will do full tests in a couple days.
    Cloudy is not good.

    You really need to know the CYA level so you can set the FC level appropriately. A few days from now may be too late.
    [center:1b48w8rw][/center:1b48w8rw]
    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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    htownjeeper's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Quote Originally Posted by filb
    A little cloudy,
    This would worry me more than my numbers. I'd probably freak out and pour a bottle of bleach in there without running another test! j/k, but not really. That's my knee jerk reaction when I think that I might be on "the edge" of having to shock. I usually end up finding out I was over cautious, but it's working out so far.

    Like Richard said, you really need to know what your CYA is so you can get your correct FC level.
    22,000 inground Fiberglass
    DE Filter Pentair FNSP 48
    Century Centurion 1.0 HP 1.25 S.F. 3450 RPM

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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Today my readings are:
    TA=150
    CH =50
    PH=7.5

    simple chlorine test: 2
    FC=2.5
    CC=.5
    TC=3

    CYA=65

    Using the TFP goals for a SWG pool, and using pool calculator, looks like I need to add 31oz 6% bleach and 6.7 oz dry CYA. So I'll do that now. Actually the bleach amount is to get a couple points higher on Free chlorine like Richard recommended . (although when he advised, my FC was 3.5, now it's lower so I'm making up for the difference) I know my TA is higher than what they recommend, but user "Linen" on another post I had, said not to worry about TA since my PH isn't rising.
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    htownjeeper's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Still cloudy?
    22,000 inground Fiberglass
    DE Filter Pentair FNSP 48
    Century Centurion 1.0 HP 1.25 S.F. 3450 RPM

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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    I can't see...I have my silver thermal "bubble cell" blanket on it to retain the heat. Days have been over 100, but nights cool down the water too much so that the next day it's too cool to swim. will chk tomorrow when I pull it off to vacuum.
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    Ohm_Boy's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    You should leave the pool uncovered during the day for a bit to get that CC taken care of. The UV will do a world of good.
    Also, your CYA may not need adjusting. Get your FC up to shock level for the CYA and watch for loss overnight. Maintain shock level and let the pool air out w/ the cover off, and it'll be just fine.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    Took the blanket off and vacuumed. Pool water looks clear enough. Maybe the chlorine last night did the job, although it's hard to see cloudiness during the sunny days....I usually notice it at night, around the interior pool wall lights.

    Added an inch or so of water too today, ran pump for awhile, measured Free Chlorine with the FAS DPD powder and R-0871 and got 5.5 In other words, I reached those "couple points" higher on Free Chlorine that Richard suggested. PH measured 7.5 still, which is good. I'll test CC at the end of the day after it's been in the sun's UV rays to let it air out and also see if that kills off some of the CC, as OHM_Boy suggested.

    Guess I can do that OCLT test, but here the sun rises around 6a.m..... I'd hate to get up at 5a.m. to just get a test sample ;-P Can you take a sample at sunset (about 6:30 pm), then wait X hrs and maybe take a test sample around midnight?
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    I didn't shock yet....but if I decide to, per TFP the Shock FC is 28 for CYA level of 70 (which I'm around..I was at 65 two days ago and added 6.7 oz to get it up to 75),
    how many days does it typically take for the FC level to come down enough (to 5, is that right?) to be safe to swim?
    Intex Sequoia Spirit above ground 16' round pool, 5,000 gals. ,vinyl liner.
    Intex Saltwater Chlorine generator/pump/filter combo system
    Test kit: TF-100

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    Ohm_Boy's Avatar
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    Re: combined chlorine is EXACTLY .5 OK to leave unless ri

    If you added CYA to reach 75, then treat the pool as if it were 75.
    You can swim at FC levels up to shock level for a given CYA level. As for how long it takes to drop, that will depend upon the CYA and sun exposure, ASSUMING that there are no organics in the pool for chlorine to attack.
    Lastly, your decision (and need) whether or not to shock your pool should be entirely based upon the results of an overnight chlorine loss test. If you are not losing chlorine to organics, then you do not need to shock. If you lose 1ppm or more, then you should shock.
    As for the time on the OCLT, obviously the longer the time between tests, the more you can count on your results.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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