To dial in my skimmers I usually start at the most closed position and adjust a teeny tiny bit until it works. Just remember to give it maybe 15 minutes between adjustments.
Also new skimmers take on average 2 weeks to break in, so that may be the issue as well.
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.