He's quit going for a ride in the overflow since I took the antagonist out. I had a really mean brown bird wrasse for about a week. She took out most of the xanthid crabs, which was great, but then she headed for my smaller fish... The gutter guard sounds like a great idea, that would keep the snails out of there too!
I just ordered a third T5, couldn't resist the deal on it ($34 shipped with everything including the reflector!) With the individual reflectors on all of them, I don't have room for any more than that, but I think three will be just right.