I like your setting but wanted to still mess around a bit.
This is what I'm trying now:
Gate fully open, air inlet 75% closed, pump speed F6
1) So initially, I start closing the air inlet until the bubbles below the collar are very small.
2) Then I do small increments of the closing the gate valve until the bubble height is up to the bottom of the cup.
3) Then I fine tune the air until the bubble size is small below the collar, slightly larger between the collar and the bottom of the cup and can be slightly breaking a little bigger above the bottom of cup.
Day 1 after above adjustment, note small bubbles below collar and slightly larger between collar and bottom of the lid and slightly larger again when breaking above bottom of the lid:
Day 2, note that bubbles between collar and bottom of the cup became smaller similar to below the collar:
I know, hard to distinguish but since you have the same skimmer, I believe you understand what I'm trying to convey, Lol!