There are many rules of thumb for converting from a biocontrol program based upon chlorination to a bromine based program. This article discusses the chemistry of these biocides and describes a framework for comparing their killing power. The method described is useful for predicting the cost impact of switching from chlorination to bromination, as well as in predicting the impact of increasing the control pH for a cooling system. The method also provides realistic feed rate starting points for bromination programs. Chloramines are considered to have an even lower toxicity.
Bromine efficacy is somewhat different.
Hypobromite is considered to have an efficacy or killing power equal to, or almost equivalent to, HOBr. Bromamines also tend to have excellent biocidal activity, possibly due to the free avaialability of the bromine associated with them. Bromamines are considered to have a biocidal efficacy almost the same as hypobromous acid. Bromamine tend to be unstable and freely release bromine. Bromchloramine is formed in the presence of oxidzing bromine and chlorine species.