CONTROLLING A FLUID TREATMENT SYSTEM

A fluid treatment system includes an apparatus (1) provided with an inlet (3) for receiving a fluid to be treated, an outlet (4) for providing at least partially treated fluid and an interface for receiving a replaceable fluid treatment cartridge (2) including at least one fluid treatment part (10, 11) for treating fluid led through the fluid treatment part (10). A method of controlling the fluid treatment system includes obtaining a target value as input. A fraction of fluid led through at least a certain one (10) of the at least one fluid treatment parts (10, 11) in a mix of fluid further including fluid led from the inlet (3) to the outlet (4) so as to bypass at least the certain fluid treatment part (10) is caused to be adjusted. The step (26) of obtaining a target value as input includes obtaining data from a machine-readable tag (23) with which the cartridge (2) is provided.