Thanks for the advice - I do see that the skimmer has collected some brown liquid in the cup... I never saw the bubbles rise up in the tube, but they must have!
I didn't answer the questions about my tank because I am actually embarrased by some of the choices I've made in setting up -- apparantly I got some bad advice and am now stuck in an unfavorable situation. For example, the guy at the LFS
told me "people cycle tanks with damsels," but the people on this board have given me something of a rough time about putting fish into a tank that hasn't cycled yet. To answer your question, I have a 29 gal
tank with 2 damsels that has been up for a couple weeks. The protein skimmer has been in the water for about 24 hours now, and it is collecting waste so it appears to be installed correctly.
Thanks again, I'm sure I'll have a zillion more questions in the coming days.