Do you think...

[midgetwaiter]

I have a 1 watt over my 15, I get about 60% coverage with it being a few inches up from the surface and at a 45 degree angle. I wish I had gone with two 3/4 watts but I got a grea deal from a fellow reefer.

Considering the focus if you want full overage you're going to have to keep it a foot above the top or diffuse the light somehow. A scuffed up (sandpaper) piece of glass or acrylic might make a good lens for that.