Cartridge vs. Dirt
No. The cartridge does not accumulate dirt. This is because the sheets are made of PET (polyethylene terephthalate), which has excellent chemical properties and nothing sticks to it, not even soup. Besides, the two draught excluders at the entrance prevent the possible remains to enter. Furthermore, in the plastic lid that exists at each end of the cartridge there are holes that make easier to expel little water or moisture that could accumulate. In addition, the cartridge is open from top to bottom throughout its entire length, so it has air recirculation. Lastly, if, exceptionally, a cartridge accumulated dirt after many years, it would not be necessary to change the entire screen, but only the cartridge.