Every Other Day Procedure.

Same process as above, but when you put the black disc into the portafilter add half a teaspoon of espresso machine cleaning powder on top.

Repeat the process until water runs clear.

Thoroughly rinse portafilter after this procedure.

Take your time and do it well. Regular back flushing with espresso machine cleaning powder loosens the build up of coffee tannins and flushes them away.