So I recently bought a whole bunch of glow in the dark and black light stuff. But i was holding off on buying actual black lights because the guy at the store seemed a little slow in the head. I want to be able to illuminate my entire room with black lighting. I just want to know how many lights to buy. My room is about 12x9. I was planning on mounting a light on each wall, which would be four lights. I just dont want to buy more than i need.