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Thread: Chlorine Demand

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    In the Industry

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    Chlorine Demand

    We're a retail pool chemical store in the western New York region and experience homeowners developing chlorine demand upon opening their pool in the spring. Why is this so prevalent at this time of year? Thanks

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    JasonLion's Avatar
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    Re: Chlorine Demand

    Welcome to TFP!

    Sometimes CYA gets broken down over the winter by soil bacteria growing in the water. When that happens, one of the breakdown products is ammonia. Sometimes the ammonia out gasses, but if it hangs around it takes a significant amount of chlorine to break it down.
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    Soil bacteria

    Thank you for your response to chlorine demand. I would like to know what "soil bacteria" is that causes the breakdown of the CYA

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    Mod Squad woodyp's Avatar
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    Re: Soil bacteria

    Microorganisms and actual bacteria that live in soil as well as decomposing materials such as leaves, grasses.
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    Re: Chlorine Demand

    See this thread for more technical info including a link to the degradation pathway and to papers describing a variety of bacteria that can break down CYA. As noted in this paper, "Cyanuric acid is degraded by a large number of soil bacteria and fungi". This includes the very ubiquitous Pseudomonas. For every 10 ppm CYA that is degraded, it breaks down to around 3 ppm ammonia that can take up to 30 ppm FC cumulatively added to eliminate.
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