Favorable temperatures (80-110°F) and availability of nutrients make cooling tower systems ideal places for microbial growth. Accumulation of biofilm impedes proper heat transfer and secretes metabolic products that contribute to microbiologically influenced corrosion (MIC). The films also may propagate and release disease-causing bacteria. Control of microbial growth is traditionally achieved with biocide combinations such as bleach, sodium bromide, stabilized bromines and various nonoxidizers. Major drawbacks are costs, safety and regulatory issues associated with bulk storage and use of these chemicals. While most such biocides achieve control provided they’re dosed appropriately and monitored by competent personnel, they constitute 30-70% of the chemical expense for a cooling tower system. As a result chronic underdosing to reduce costs is common. The biocides are highly corrosive and typically fed under pressurized lines that may burst or leak.