Mark, So far just the clowns, but I plan to get a group of Bangai Cardinals some day, and if my Grammas ever spawn, they'll go in the system too. I had considered a UV unit, and may still add one. Just don't have an extra laying around right now, and all my money is going to more crucial components right now.
On a good note, I have successfully drilled 4 tanks now, with no errors, and my home-made bulkheads ($2 a peice) are working perfectly! Here's the process....
First, I traced the outside diameter of the part that must pass through the tank onto the glass with a Sharpie permanent marker. I bought these Dremel bits at WalMart - $5.50 for the package of two. I use the one that has a small ball on the end to drill a small hole, and then traced the circle out with the cone shaped bit. The pack is Dremel #7150 - Diamond Point Set. If you can't find them locally, Home Depot type places carry the #7144 (cone shaped one) or equiivelent 7134. I haven't found the ball type one anywhere singly, but it's a #7103. The two pack from Walmart costs less than one single bit at HD though.
I set the tank on a towel on my patio, turned the water hose on to a trickle, and kept water running over the whole area while I drilled. The initial hole takes about 1 minute to drill. Then you push the cone shaped bit through the hole, and cut your way around the marker line. The cone shaped bit has diamond stuff from the tip to about 1/2" up, so it cuts the entire thinkness of the glass in one pass, no multiple tracings required. The hole takes about 3 minutes to trace.
The bulkhead uses two PVC parts, and two O-rings. The bulkhead consist of 1 P/N 34275 (3/4"X1/2" Bushing) and 1 P/N 30405 (1/2" MIP Adapter (SXMIP)). Both are Genova part numbers, and can probably be cross-referenced by your local shop.
The O-Rings are made by Danco, and are listed as a #15 (1" O.D. x 3/4" I.D.) Pack of ten for 2 dollars in the kitchen sink section of HD.
Here's a pic of the hole, it's not perfect, but the O-Rings seal it up tight.
And the assembled unit, a 3/4" PVC elbow fits perfectly on the outflow, which will connect to 3/4" pipe back to the sump. The I.D. of the peice inside the tank is 1/2", so I found some 1/2" O.D. drain covers (replacement parts for Maxi-Jet 900).
The installtion goes - put one o-ring on the part that goes through the tank, slide it through from the inside, add another o-ring from the outside, and screw the second part onto the first. Simple, cheap, and leak proof!