Thanks everone. I just got back from Mills Paint (excellent customer service btw
) as I did a search and found out they sold marine paint. According to them however, marine paints contain fungicides and other nasty chemicals which harm aquarium animals, and should be avoided. He then went on to mention something called "potable water" which is supposed to be a paint used to line drinking water tanks and such which may be a better bet. I'm going to do some research now on this stuff.
I thought about lining the canopy with a reflective material as well, but the thought of all the work involved and the fact that I just read somewhere (here, RC...can't remember) that white would be the best for reflection.