I am in the 3rd day of cycling a 55g tank and the skimmer barely produces any thing.
Thats kind of normal. Skimmer wont produce anything if there is not much in the water to skim out.
I belive the directions for the skimmer you have say to adjust the ventri so the water line in the main chamber is just below the rubber gasket that seals the collection cup. Thats the line where the microbubbles should be. Larger bubbles will rise above that and eventually up into the collection cup.