Quartz sleeve scaling significantly affects the efficacy of ultraviolet (UV) processes for water treatment. Investigating the scaling process and developing prediction methods are important for selecting and optimizing scaling control measures. However, these have been limited by the lack of an appropriate experimental system. Therefore, this study investigated the kinetics, mechanisms, and prediction methods of calcium scaling (a predominant scale compound encountered in drinking water treatment) on quartz sleeves. An on-line experimental system for sleeve scale UV transmittance (UVT