Bluelab EC 2.77 / 1385 ppm standard solution 500 ml
Calibration solution for Truncheon, Guardian (conductivity), and ppm/EC pen.
2.77 EC = 1385 TDS/ppm (500 scale) = 1890 ppm (700 ppm)
Bluelab's EC/CF equipment does not need calibrating as they are all factory calibrated at Bluelab. The CF27.7 (EC2.77) solution is used as a reference or checking solution to ensure you have adequately cleaned the EC/CF probe.