Removal of limescale: unscrew the lid and remove the tube with the electrolytic cell on it from the tank. Disconnect the power supply, hang the tube with the electrolytic cell in a bottle filled with approx. 6 cm of cleaning vinegar or citric acid ( the bottle is reuseable! ) After a while the electrolytic cell is completely clean and free of limescale. (with cleaning vinegar heated to 60 to 70 °C it goes faster!)
Put power back on the system and TIP: Check whether there is ozone production by dipping the electroyse cell in a glass of water. Now you can see it better than in the tank!
Dry the electrolytic cell, hang the tube with the electrolytic cell back into the tank and tighten the lid again.