A comprehensive monitoring and control package, has been deployed at several industrial and HVAC open recirculating cooling water systems, over the past two years. Use of this package has resulted in improved heat transfer and extended equipment life, through 24/7 control of the three main challenges encountered in cooling water systems: scale and particulate deposition, microbiological growth, and corrosion. Automation of this “cooling water triangle” utilizes new fluorescent-based sensing technologies that detect actual system performance and turn the data into knowledge via proprietary control algorithms. The complete package includes new, robust chemical treatment programs and advanced remote communications and data management capabilities. The new automation package has been extensively tested in the field. This paper describes performance results from these applications, including the economic payout to the user, reliability and accuracy of the instrumentation, response to unit upsets, and the minimal operator involvement required to operate and maintain the system.