This procedure is only applicable for LAQUAtwin Na-11, K-11, NO3-11, and Ca-11 models, which have special set-up mode to show reading in mmol/L unit. Note that the mmol/L unit itself is not indicated in the special set-up mode and will not appear on the LCD after following this procedure. 

1. Press ON/OFF button to switch off the meter.

2. Press and hold MEAS, CAL, and ON/FF buttons simultaneously for 3 seconds.

3. Wait for the meter to display Init.

4. Press and hold MEAS button for 5 seconds. The meter will display ON and switch off automatically.

5. Press MEAS and ON/OFF buttons simultaneously for 3 seconds.

6. Wait for the meter to display unit setting.

7. Press MEAS button repeatedly until both ppm and mg/L units disappear and Unit alone is displayed.

8. Press CAL button repeatedly until the meter switches off.