If this is in the wrong area, please fill free to move it.
I'm getting a glass hood finally and well my light is a shop light from Wal-Mart. So it's not really designed to sit on the aquarium. So I'm looking to suspend it from the ceiling like it's designed to be. I was looking to have it about 4 inches (About 9.6CM for our metric friends out there) over the hood that intern sits a good 1.5 - 2 inches (3-5CM) over the water.
My question is. Is this going to affect the intensity of the light so much that I might want to consider more light? Currently I have 80Watts of light for about 40 gallons of water.
Yes. Shoplights are designed to illuminate rooms. Aquarium lights tend to light straight down. The difference is in the shape of the reflectors. You can buy a new deflector, or make your own to direct almost all of the light down into the tank.
10 Gal Planted, 3 wpg, Eco-Complete and Tahitian Moon Sand
JMO but I think too much of that light will be diffused away from the tank. As greenmagi says shop lights are intended to light a room, not reflect light into an aquarium. It' the shape of the reflector as much as anything else which concentrates the light. Merely adding reflective mylar may make it brighter but won't really concentrate the light back into your tank.