skimmer help

[Nemo]

I had the same questions with mine. my level would be good and then it would just drop 8-10" and no skimming. I found out that after a feeding the oils and junk in the water would not allow the larger bubbles to form that gets the protiens out. (something about oils and surface tension) But now it is working great and I know not to touch the settings when things do not look right.