Just wanted to make sure the air tubes were clear, they appear to be fine though since you got a response when covering them. Is this a brandy new skimmer? That might have something to do with it as well.
I don't think you are doing anything wrong, don't worry.....skimmers can be a pain to dial in sometimes for everyone....
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.