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Thread: Health effects of high chlorine levels?

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    Health effects of high chlorine levels?

    Perhaps this will land in the controversial topics part of the forum, but after studying the CYA / Chlorine chart, I have to ask a question. I hope I don't get branded a heretic!

    I get the whole concept that the CYA binds up part of the chlorine and from the standpoint of preventing algae, the higher levels of chlorine are needed. What I'm struggling with is the following from the Iowa state code for public pools (and other states seem to have similar rules):

    "Bathers shall not be permitted in swimming pools when the disinfectant chlorine residual is greater than 5.0 ppm."
    http://www.legis.state.ia.us/Rules/Curr ... /64115.pdf

    This makes me think that the State of Iowa at least thinks (not that state legislatures are ever wrong!) that something is bad about levels > 5.0PPM. I'd sure like to understand that in addition to killing algae that there are no potential dangerous side effects from higher levels of chlorine.

    This seems rather scary..
    http://www.gasdetection.com/TECH/cl2.html (a lot of it is about chlorine gas, but some references to skin irritation at levels above 5PPM)

    Is the CYA enough to prevent side effects of the higher chlorine levels?


    I've read several posts here about the relationship between chlorine / CYA and algae prevention... is there a post that addresses potential health issues?
    ----------------------
    20,500 gal gunite pool w/ PebbleTec and infloor cleaning system.
    Sta-Rite System 3 cartridge filter.
    Houston, TX

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    JasonLion's Avatar
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    Re: Health effects of high chlorine levels?

    FC levels above 5 do indeed cause problems when CYA is zero. The idea that CYA has anything to do with it at all is very new, ie 40 years old, compared to the rate at which state rules get updated. A large number of places still use the rules they were using 50 years ago, when no one understood how CYA worked.

    The bio-activity level of chlorine is far far lower in the presence of CYA, so the effective chlorine level is much lower. That impacts almost all of the effects chlorine has, including skin irritation. About the only situation where it doesn't behave exactly as if the chlorine level was lower, would be if you drink the water. And even there, the difference isn't as large as it might seem because the time constants are fairly long.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    reebok's Avatar
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    Re: Health effects of high chlorine levels?

    this question comes up fairly often (I asked about it myself) and I can tell you that running my pool per the chart (target 8ppm for cya of 70) has presented no problems and prevented many like algae and other viruses, bacterias, etc. for me, my wife and daughter who has been in it since 10 months of age.
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: Health effects of high chlorine levels?

    Quote Originally Posted by CurtisT
    Is the CYA enough to prevent side effects of the higher chlorine levels?

    I've read several posts here about the relationship between chlorine / CYA and algae prevention... is there a post that addresses potential health issues?
    The short answer is yes, the CYA significantly reduces the active chlorine (hypochlorous acid) concentration and that significantly reduces chlorine's reactivity for killing pathogens and oxidizing chemicals (including skin, hair, etc.) including, in some cases (such as for nitrogen trichloride) the creation of disinfection by-products. I responded to another post referring to state codes here.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Health effects of high chlorine levels?

    Thanks for the responses. I also noticed in the other thread Richard mentioned that someone pointed out that the Florida codes allow for up to 10PPM (http://www.pooloperationmanagement.com/ ... lorida.htm). That gives me some extra confidence as well.
    ----------------------
    20,500 gal gunite pool w/ PebbleTec and infloor cleaning system.
    Sta-Rite System 3 cartridge filter.
    Houston, TX

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    Re: Health effects of high chlorine levels?

    Quote Originally Posted by CurtisT
    Thanks for the responses. I also noticed in the other thread Richard mentioned that someone pointed out that the Florida codes allow for up to 10PPM (http://www.pooloperationmanagement.com/ ... lorida.htm). That gives me some extra confidence as well.
    AND I have a feeling that there are a LOT more pools in Florida than Iowa!

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