The intricacies of automated chemical controllers

By Lance Fitzsimmons

Proper water balance in commercial pools and spas can be the difference between a safe, attractive facility and a disastrous one. Advances in chemical automation, disinfection methods, and better education on the problems associated with water chemistry have made the aquatic facility operator’s job easier when ensuring pool and spa water is safe for bathers.

Oxidation reduction potential (ORP)/pH controllers have been used since the mid-’70s; however, these systems were large and expensive. As a result, they were typically used primarily by municipalities and large aquatic facilities. Some of the greatest innovations were introduced in the early ’90s when microprocessor technology superseded analog equipment. The introduction of the two-pool controller with modem communications became an extremely powerful tool which allowed facility operators to monitor and control pool/spa water remotely.

In fact, remote communications has made it possible for facility operators to become proactive in pool/spa water management. Whenever water chemistry falls below the established threshold, the chemical controller is capable of sending a message to a facility operator’s mobile device, in addition to allowing him/her to log in to the controller, to diagnose and correct the problem before it becomes a health issue.

Chemical automation using direct connections from microprocessor-based programmable controllers to a wireless Internet database management system provides facility operators with real-time water chemistry data. Programmable chemical controllers have now become the reporting media, transferring information from the aquatic facility to a ‘readily accessible’ record of the water’s current and past status. Using this technology, facility operators can monitor and control the water’s chemical balance with more accuracy than in the past.

Despite the fact these devices are now commonplace in most aquatic facilities; many do not fully understand how they work. ORP is a qualitative measurement, not a quantitative measurement, and is affected by many factors, including the biggest variables in pool/spa water chemistry, such as pH, cyanuric acid (CNOH)₃, and salt.

Health departments require a specific range of chemical residuals, which leads people to look at ORP and parts per million (ppm) charts to establish chlorine residuals mandated by local health authorities. This situation can be confusing for some facility operators because the water is often in compliance with ppm, pH, and cyanuric acid, but has unacceptably low ORP levels to effectively oxidize and sanitize the water. Conversely, there are also pools and spas that are well below the required ppm levels, but have exceptional water quality.