That actually not a bad idea. I have a old Fluval that I am sure I could rig up, and get it to work. I have all these BioPellets, and no place to use them. I think they could work wonders on his tank.
I would use the JBJ Chiller Installation Kit and the BRS Single Reactor or some other reactor. If you can fit a maxi jet 900 in the rear chamber, do that. If not, use an external pump, but use ball valves on both the input and output hose in either case if you go with this setup. This is what I use on my 28G JBJ nano cube and it works well.