Hello Im running 2 MH HQI 150Watt and 2 PC ANT on a 75gal. I built mine 12inch high
ran 2 fans blowing and 2fans blowing out. As for paint and such i went to the paint store got some sealant good for 50year and has good flex also picked up a can or marine primer and 2 cans of marine paint gloss. I then used the sealant on all corners, screws, crack or whatever i saw, then primed it all 2 coats then painted the inside of the hood white with marine paint and black on the outside.
Now it looks good nice and smooth easy to clean pretty much water proof.