5
Calibrating the pH-electrode
5.1 Purpose of calibration
Any measuring instrument can only be as accurate as the connected sensor. The pH-electrode is
thus a vitally important part of the pH measuring device. As the setting of any pH-electrode may
drift in the course of time, in order to ensure a constantly high quality of measurement results it
is vital to calibrate the pH-electrode on a regular basis.
5.2 Preparing for the calibration process
For optimum calibration values, the calibration solutions should have a temperature of 20-25 °C.
To prepare for the calibration process, pour sufficient pH 7 calibrating solution from the bottle
into a separate, clean receptacle to ensure that the electrode is submerged by 2 cm at least. Pour
a little pH 4 calibrating solution into a second receptacle and a little distilled water into a third
receptacle.
5.3 Calibration procedure
The user-friendly calibration process provides for swift, reliable and convenient calibration of the
pH-electrode :
• Rinse electrode briefly in distilled water.
• Place electrode in pH 7
calibrating solution.
•
Wait approx. 1 minute
for the electrode to adapt to the calibrating solution. Adaptation
is complete when the displayed measurement value no longer alters. (Note: When calibratin
with pH 7 for the first time after initial start-up of the device, "E" will be shown on the display,
instead of a measurement value. One calibration process requires to be carried out success-
fully in order to display the measurement value).
• Press
button "pH 7"
: The yellow LED flashes, the devices now calibrates automatically at
pH 7, the display shows "E 7".
• When pH 7 has been successfully calibrated, the LED will go off and "7.00" will appear on the
display. The LED on button "pH 4" now lights up.
• Remove electrode from pH 7 calibrating solution and rinse briefly in distilled water.
Place electrode
in pH 4 calibrating solution
. Wait until the displayed measurement value
no longer alters.
• Press
button "pH 4"
: The yellow LED flashes, the devices now calibrates automatically at pH 4,
the display shows "E 4".
• When pH 4 has been successfully calibrated, the LED will go off and "4.00" will appear on the
display. The "Calibration reminder" LED also goes off.
This completes the calibration process. Rinse the pH-electrode with a little distilled water and hang
in the aquarium in the electrode holder. The calibration process takes around 5 to 10 minutes,
depending on the condition of the pH-electrode.
Dispose of used calibrating solution.
The pH-Controller is now ready for use.
The display shows the current pH value in the aquarium.
27
pH 7
pH 4
5
6
7
8
9
