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Thread: UV and Chloramines

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    In the Industry

    Join Date
    Jan 2011

    UV and Chloramines

    UV systems have been by all accounts, a very effective means for treating chloramines ( along with proper ventilation, filtration, etc) in indoor pools. Commercial outdoor pools typically have very low levels of chloramines. With air circulation being a non-issue, how much can the Sun's UV rays account for the destruction of chloramines in outdoor pools? Probably impossible to quantified that. If chloramines are found to be elevated in an outdoor pool, could it be suggested that the sun is treatment itself?

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    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: UV and Chloramines

    For a residential pool that is typically low bather-load, the UV in sunlight along with outdoor air circulation is sufficient to make chloramines a non-issue. However, in a high bather-load pool, the UV in sunlight may not be enough to control chloramines. The UV in sunlight is not in the strongest absorbing region for chloramines. This graph shows that the molar absorptivity for dichloramine extends beyond 300 nm wavelength where the UV in sunlight cuts off (sun irradiance peaks at around 1.5 W/m2/nm in the 500-600 nm range, but drops to 0.5 at 350 nm and to 0.15 at 320 nm, 0.03 at 310 nm, 0.002 at 300 nm and 0.000003 at 290 nm).

    Since dichloramine is an intermediate towards nitrogen trichloride in the chlorine oxidation of ammonia, the sunlight helps, but it doesn't compare to a UV system which is better suited to high bather-load situations and indoor pools.

    Note that UV in chlorinated swimming pools may be a mixed bag as noted in this paper where some chloramines may be reduced, but some other byproducts such as cyanogen chloride may be increased. It is not a panacea.
    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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