Bluelab Guardian MonitorBLUELAB GUARDIAN MONITOR The Bluelab Guardian Monitor measures pH, conductivity and temperature. It is a constant indicator of the desired levels of pH, EC ppm 700 TDS CF and temperature, enabling you to optimise these critical parameters through each growth stage. It has a large easy to read display. It is mains powered and can be mounted to the wall or hung on a support with the probes simply placed into the reservoir. The Bluelab Guardian Monitor