If that bulb is really close to the glass, i would be concerned about it being a "cooltube" perse. What really makes a cooltube great is being able to not only pull the air from the bulb, but also pull from the room. I'm not sure how that bulb will be if you have it in such a tight confinment, the life of the bulb might be compromised, but i'm not 100% on that. It looks great, the only thing i think i would change would be to get a bigger glass, and connect some tubing to the end to your fan, you have a 500+cfm fan so you should have no problem pulling air out.

Another than that, great job.