What symptom indicates a deep clean is overdue for a Metal Filter made of stainless steel mesh?

Slowing down the flow rate or producing significantly muddier coffee than normal.

Metal filters, typically constructed from fine stainless steel mesh, do not absorb oils or retain flavor compounds like paper or cloth; therefore, their operational failure is generally related to physical obstruction rather than chemical degradation. While daily rinsing is routine, mineral deposits and baked-on coffee oils can accumulate within the microscopic openings of the mesh over time. When these tiny pores become clogged, the water flow rate is noticeably reduced, or the filtration quality degrades, leading to a significantly muddier final coffee product, signaling that the necessary periodic deep cleaning with a dissolving agent like vinegar or equipment cleaner is required.