Mister Limpet, UGF's have been pretty much phased out of the aquarium life. the invention of the HOB filters really drove the UGF's out of business because of issues that people have had.
Proper cleaning of the gravel can prove they still work well, but the ease of HOB and canister filters outweighs the maintenance of the UGF's. So that is why now a days people recommend HOB over the UGF. easier and better filtration. but you are right, back in the day, UGF's ruled!
But back to the OP.
what is your feeding schedule?
I would suggest removing the UGF and getting HOB filtration that is rated to 60gallons at the min.
The species I suggest you rehome are the angel and the redtail shark.
The gourami can be your showcase fish for the tank...and a very pretty one at that.
But the angel+gourami=1 dead
the redtail shark needs a minimum of 4ft long tank, and in a 30gallon, he'll destroy your cory's with his aggression.
if you remove those two fish, up your cory's to 6, and then get quality school's for your tetra's. you will have a fantastic tank.
That is a fantastic idea! My current feeding schedule is 08:00, 15:00, and 20:00. This gives me an excuse to get my old 55 back in operating condition. As for the 30g I am really liking the idea of an HOB, but am a tab bit confused on the aspect of protein skimmers. Sorry for the noobie question, but could somebody please explain them to me?