Measurement of Dissolved Oxygen Concentration
Plug the dissolved oxygen (DO) sensor into the slot #2 (by default) and a DS thermometer into the slot #1. Then, press keypad "C6" to measure or to start the calibration processes.

Hints on preparation and calibration of the DO sensor:
Before first use of the sensor, prepare 0.5 mol/L sodium hydroxide (NaOH) solution by measuring 20g of sodium hydroxide and dissolving it in 1000 ml of water (let the solution cool down for around 30 minutes). Add the solutioninto the membrane cap (around 2/3 of volume) as the filling solution.

For calibration, wet the probe in pure water and shake off excess water drops. Expose the probe to the air for a few minutes. Select Calibrate from the lower right menu (or press keypad "D#"). You may need to repeat the last step several times until the calibration reading is stable.