Skimmer collection cup?
 

Does the skimmer collection cup work better when the chamber is clean or dirty? The reason why I ask is that, I notice after I clean the cup it takes a while for the skimmate to start coming up the cup again.

A little bit of both...the ideal is cleaner than dirtier... when you first clean it, it will take a while for a film/slime to form. Once it does this is ideal...

Once to much forms then it doesn't work as well.

(This is my understanding)