Check out this background effect was able to achieve:
I noticed on some pics of tanks at the ADA headquarters that none of the tanks had backgrounds. That seemed to give them the appearance of more depth. When my "taped on the back of the tank" background fell off, as it tended to do on a regular basis, I left it off as an experiment. When I decided to take some pics I didn't like the idea of the wood paneling coming through so I compromised and taped the background to the wall, instead of the back of the tank. I am very happy with the results.