If you want to combat scale buildup in your Quick Mill Pathfinder, follow the procedure outlined in this article to properly descale your espresso machine.
Single boiler heat exchange machines can be descaled by the consumer. Since descaling is not the primary cleaning method for prosumer-style machines it does not need to be done frequently. Descaling can be done on a 3-4 month basis, or whenever the machine starts to display flow issues. If hard water is being used in the machine, or the machine gets heavy usage, the machine may need to be descaled more frequently. The video below describes the process for descaling a single boiler heat-exchange machine.
How To Descale Espresso Machine Heat Exchange Boilers