In 2010, one of the Power Plants of Puerto Rico Electric Power Authority (PREPA) faced a crisis due to biological growth in their power plant’s cooling tower. The plant was using straight hypochlorite, which was not effective at controlling biological growth. Consequently, plant heat exchangers were plugged and temperature rose above manufacturers specifications due to biofouling of the condenser tube sheets which inhibited effective heat transfer. Due to the biofouling, the units were operating above their limit at 5 or 6 grades over manufacturers specifications even with the valves fully open. The heat exchangers were incapable of removing all the heat, which resulted in a drop in the plant’s energy output.