Extremely simple filter change

Filter change: Close the water supply valve, unscrew the old filter cartridge clockwise and pull it down. Insert the new filter cartridge from below and screw it in counterclockwise until it stops. Re-open the water supply.

When should it be replaced?

The filter cartridges have to be replaced regularly. Precise information about the replacement intervals can be found in the relevant item table.
However, an earlier replacement may be necessary if the water flow is noticeably reduced. This is generally an indication of the increased occurrence of fine particles in the unfiltered water.