first time using skimmer

I bought a new skimmer and this is my first time ever using one.

It is a hang on the tank type and is rated for 180 gallons, but I have it on
an already established 30 gallon tank. Reason I got it so big is I plan on
setting up a 55 gallon in the near future.

Anyway, it seems to operate...the column is filled with bubbles. But no
gunk is coming out and the return water puts lots of micro bubbles in my
tank.

Am I doing anything wrong, or have I just not had it set up long enough.
This is the first day its in operation.

I even stirred up the tank so that some of the crap rose up into the tank
hoping it would suck alot of it out.