Connect the combination pH electrode to the input socket and calibrate the electrode. Set the Selector Switch to the pH position or ATC (Automatic Temperature Compensation) to give accurate pH at any Temperature and under specific weather conditions. Wash the electrodes with distilled water and dip the combined electrode in the solution under test. Set the 'Desired Temperature' to control the solution temperature. The display shows the pH value of the solution directly in pH units. Between measurements, leave the electrode immersed in distilled water and Function Selector Switch to 'Stand By' position.