Descale your Xelsis when the machine indicates this, or after 8 AquaClean filter replacements.
The process takes about 15-20 minutes and the display will guide you trough all steps.
Note: only use Philips descaler CA6700
Tip: Using the AquaClean filter reduces the need for descaling.
Warning: under no circumstances should you use a descaler based on sulfuric acid, hydrochloric acid, sulfamic or acetic acid (vinegar) as this may damage the water circuit in your machine.