Calibration purpose

[barnaby97]

Hello can I know what is the purpose of calibration purpose, Since the starting value in serial monitor after each calibration depend on the value of buffer solution. For example if I used 500ppm buffer solution, the value in the serial monitor will be 300 after I take out the probe from the solution. While if I used 707ppm buffer solution, the value in the serial monitor will be 500ppm after I take out the probe from the solution. I notice when cal:tdsvalue is being put, there is new K-value been rewrite