Bromamines are considerably less stable than chloramines in receiving waters. Bromamines tend to break down into relatively harmless constituents typically in under 60 minutes. Consequently, BrCl is less damaging to marine life than chlorine. Chloramines at concentrations below 0.1 ppm have resulted in fish kills. There are also indirect effects from chloramine contamination. For example, fish populations tend to avoid toxic regions, even at very low levels of concentrations. Consequently, large areas of receiving waters can become unavailable to many species of fish and even cause blockage of upstream migrations during the spawning season. It should be noted that although chlorine efficiency is increased by nitrification, BrCl performance is not. Because of the high biocidal activity of bromamines, it is not necessary to utilize high concentrations and breakpoint conditions to achieve active halogen residuals, as is the case in chlorination. The breakpoint reaction with BrCl is achieved almost immediately in the presence of even slight excess amounts of bromine at pH levels of 7 to 8. There is, however, no need to reach the breakpoint to achieve good disinfectant properties with BrCl. In contrast, with chlorine it is necessary to add amounts in excess of the breakpoint to obtain sterilizing characteristics,
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