Cooling towers are a prime environment for the buildup of microorganisms. Maintaining control of this buildup is essential for efficient operation of the cooling loop. This can be successfully achieved with the use of chlorine dioxide. Microorganisms build slime layers and other colonies, which can result in several serious problems: increased deposits, buildup of odors and slime due to the adhesive nature of the biofilm layer, loss of heat transfer due to the insulating nature of inorganic deposits, increased corrosion rates due to “under deposit corrosion,” and increased consumption of power due to the restriction by the deposition. The injection of chlorine dioxide into the recirculation of the cooling towers alleviates these issues and also causes less wear and tear on the equipment.