So how may 4oz. bottles do you think it will take to paint a 150gl tank?
Sorry couldn't resist
I used about 1/2 of a 4 oz bottle to do my 55 with 2 coats of paint so 1 4oz bottle would be enough to get at least 2 coats on a 150. At 1 - 2 $ per bottle it's cheaper and much less toxic then spray paint and even latex paint. And the craft paint is fairly thick so thinning it with a little water will net you a bit more then 4oz probably closer to 6oz.
Honestly it doesn't have to be 100% opaque unless you have a light source behind the tank your trying to block out