BL121 Swimming Pool & Spa Controller Control with Confidence The BL121 Swimming Pool Controller is a complete system designed for maintaining swimming pool, hot tub, and spa disinfection water quality. The BL121 is available in two configurations. The basic version is the in-line model which allows for direct installation of probe and chemical injection fittings...

pH 500 series of controllers are simple to operate, microprocessor-based process meters packed with features. For more flexibility and better resolution for chart recorders, any two points between 0 and 14 pH can be chosen to correspond to the analog output spans.