Very nice tank! I think that's a cool idea with the pvc pipe too!! My clown loach took over my pleco tube so my plecos are guarding eggs inside a hole in the driftwood!!
I just set up my 10g cherry shrimp tank. I'm going to borrow your pvc pipe idea so the shrimp can explore in it. You know what would be cool? If you made an ungravel tunnel. just make it like a maze with like 5 or 6 different exits/entrances