Is your conductivity instrument adequately cleaned and giving accurate results? Test and see...

Most of Bluelab’s EC/ppm equipment does not need calibrating as they are all factory calibrated at Bluelab (except Bluelab EC and ppm Pens). The 2.77 EC solution is used as a reference or checking solution to ensure you have adequately cleaned the EC/CF probe.
 
Bluelab solutions are manufactured specifically for Bluelab products are NIST certified and are made to a traceable standard to ensure your Bluelab products last longer and maintain accuracy.