Grundig HD-1901A Manuel D'utilisation page 9

Cleaning
To extend the lifespan of the appliance, it is recommended to clean it at
least once a week.
l Switch off and unplug the appliance.
l Do not immerse the appliance in water to clean it.
l Wipe the base with a soft damp cloth and wipe it dry. To avoid
scratches, do not use abrasive cleansers or hard brushes. Do not
immerse the base in water or put it under running water.
l Fill the water tank about half full and add ¼ cup of vinegar. You
can use a soft brush to clean the tank. Remove the water and rinse
the tank thoroughly.
Note: The water tank should be cleaned once a week.
l Use a solution that is ½ vinegar and ½ water to clean the ultrasonic
disc. Pour the solution onto the disc and leave for at least half an
hour. Use the soft brush to gently clean the disc. Pour out the
solution and rinse with clean water several times.
Note: Be careful not to get water on the digital display, the electrical
components of the base or the power cable. Do not immerse the
base or cable in water.