Now that my IN 100 has been running for a couple of days, how far do you need to close the adjustment tube to actually get skimmate? I ran it open for a couple of days and didn't really get any. (I know it needs to 'break in', but I did run it in a vinegar solution for about 5 hrs prior to putting it in the tank.) Right now to get any skimmate in the cup I need to set it almost to totally closed. (I ran it almost closed for about 6 hrs. and got a tiny bit in the bottom of the cup.) Is this normal?