when you first get a skimmer, do not try and set it to skim right away. the skimmer needs to break in. OPEN the effluent adjustment knob all the way and let it run for a few days until you get a stable foam head. Once you get a stable foam trying to push up to the cup, SLOWLY close the effluent a full 360 turn at a time. After each adjustment just leave it for a day, then close it another turn, wait another day (and so on). Once the foam head is stable and high enough to push into the cup, lust leave it and let it do it's thing.
Adjusting it out of the box to skim will only cause frustration because each tweek has to have time to re-adjust and stabilize. If you don't give it enough time between adjustments you'll start over each time and want to throw a skimmer out the window LOL
hang in here and open it up (full air too)