Nice, thanks for the suggestion. Based on the reading, it looks like it would have to be a final addition after the tank has matured.
I made a rather interesting discovery over the weekend. After the discussion of water volume I had decided to drill the tank to add a sump and I had also decided I wanted to increase the tank size to a 40B. So over the weekend while doing our Christmas shipping in the larger community two hours to the north of us, I picked up a 40B at the not so local PetSmart. Hauled it into my classroom, and guess what? Yep, thats right, the tank I already had, which I thought was a 30B is actually a 40B! Not sure how I messed that one up, but out well. Maybe I'll use the second one as the sump.