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Thread: Bleach raises CYA?

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    Bleach raises CYA?

    Does adding bleach increase CYA levels? I read that DiChlor does, was wondering if bleach did too.
    Lafayette LA, 30-35k gal, Sand Filter Tahitian HR25, IG, Gunite

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    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Bleach raises CYA?

    As described in How to Chlorinate Your Pool in the Pool School, bleach and chlorinating liquid do not add anything extra to your pool other than salt. They do not add Cyanuric Acid (CYA) nor do they increase Calcium Hardness (CH).

    The following are facts of how much extra is added by various chlorine sources and is independent of concentration of product or of pool size:

    For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
    For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
    For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

    For every 10 ppm FC added by any source of chlorine, it results in at least 8 ppm salt when the chlorine gets used up. For bleach, chlorinating liquid and lithium hypochlorite, an extra 8 ppm salt is added upon addition (so a total of 16 ppm salt from use of these products). Salt is fairly innocuous and builds up much more slowly in percentage terms since a salt level of 1000 ppm is not a problem while generally a CYA above 100 or a CH above 500 are usually problems.

    Even if one had a rather low 1 ppm FC per day chlorine usage/consumption, then continued use of Trichlor would result in an increase in CYA of over 100 ppm in 6 months if there were no dilution of the water. With Dichlor, the CYA would increase by over 160 ppm while with Cal-Hypo the CH would increase by over 120 ppm. Bleach, chlorinating liquid and lithium hypochlorite would increase salt by over 280 ppm while most other sources of chlorine would increase salt by about half that amount.

    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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