My skimmer is not producing any skimate. My tank is only 4 weeks old is this normal. I have adjusted the air intake for the past few weeks and still no foam makes it into the collection cup. I bought the skimmer at a LFS. It is similar to a backpack skimmer in design. The store owner makes these skimmers and uses them in all of his display tanks. Did i get riped off or does it take longer for the skimmer to work.