The % setting on Optical DO Probes purchased prior to January 2015 is 0-100%. Optical DO Probes purchased after January 2015 can measure from 0-300%. If you are unsure of the purchase date, check the serial number or the stored factory calibration.

Serial Number
The serial number is located on the box containing the microSD card. If the serial number starts with DOV1, the Optical DO can measure between 0-100%. If the serial number starts with DOV2, the Optical DO Probe can measure between 0-300%. See the images below for reference.


Factory Calibration
1) Position the switch to %.
2) Connect the Optical DO Probe to the data-collection interface and start the data-collection program.
3) Choose Calibrate from the Experiment menu (Logger Pro) or the Sensors menu (LabQuest App).
4) Choose Equation (Logger Pro or LabQuest App).
5) Compare the information to the following calibration values to identify the range.

0-100 % range
Intercept: -2.2222
Slope: 22.222

0-300 % range
Intercept: -6.6667
Slope: 66.667