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Thread: Safe Free Chlorine level

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    Safe Free Chlorine level

    I have a question about free chlorine maximum levels. I have always used 5 as the maximum number I would swim in, but tonight I started reading some info on the internet that seemed to conflict that a bit. I was not looking for this, but found it while I was looking for info. about kill times of stabilized vs. unstabilized chlorine. South Carolina's Dept. of Health and enviornmental Control's pool guidelines showed 8PPM free chlorine as the maximum for a stabilized or non stabilized pool. Ga. Dept of Public health showed 10PPM as the max for a stabilized pool and 5 as the max for unstabilized pool. All the conflicting info. confuses me a bit.

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    duraleigh's Avatar
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    Re: Safe Free Chlorine level

    All depends on your stabilizer level. There is an FC/CYA chart in Pool School that shows that relationship, It is fine to swim up to those published shock values.
    Dave S.
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    JasonLion's Avatar
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    Re: Safe Free Chlorine level

    The maximum FC level you want depends on the CYA level. CYA holds chlorine in reserve, so there is less active chlorine the higher your CYA level. To compensate for this, and get the same level of disinfection, you need to raise FC as CYA rises. Most public health laws fail to take this into account, and are either far to conservative, or far to aggressive about FC levels because they implicitly assume some CYA level.

    In Pool School there is a chart of appropriate FC levels based on your CYA level. Swimming is fine from the minimum up to shock level for your CYA level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Safe Free Chlorine level

    Just to make sure I understand right, if my CYA were 100, I could safely swim at 38ppm F.C?

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    JasonLion's Avatar
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    Re: Safe Free Chlorine level

    Yep. And if CYA is really really zero then you don't want to swim above FC of 2.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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