I am setting up my first tank. I found a used Aqua Medic Turboflotor
1000 with a Rio 2100 on ebay (one needle on the impeller is broken).
When I set it up, it creates pea sized bubbles in the chamber, though
not so many as to make it difficult to see though the chamber. At the
LFS, I saw some other skimmers in action that created a mass of
pin-head sized bubbles that completely obscured the view through the
chamber. This is what I was expecting to see with my new (used)
skimmer, but what do I know (first time and all).

Several posts talk about making sure the connections between the pump
and the skimmer are tight, so I used Teflon tape on these. The air tube
is clean and the venturi holes are open.

Pea sized bubbles are way to big. You need to buy a new a new needle wheel:
http://tinyurl.com/ycanc6