I painted my 150 black. used a roller with flat black acrylic enamel.
used 3 coats with the recommended drying time in between coats.
Steve I'm sure you've seen enough tanks to make sure of your selection of color. They say that a black back gives the tank depth, but sometimes
I kind of wish I would have used a blue color to brighten things up.
I tried to use the stick on backing but I got bubbles and wrinkles in it - it looked horrible. Then I spray painted it blue with Krylon - now it looks great. Used 4 coats, very easy to apply, can costs $3 or so from walmart.
I used a roller and I highly recomend the Blue oil based paint sold by Ace Hardware. Their blue is a little darker than the Home Depot paint I used. Rob used the Ace Hardware paint so next time you are in his store take a look at his tanks. They have a nice look over the swimming pool look of most blue paint sold at the other two hardware stores in town.