Quote Originally Posted by britewire
I've heard some people say that the glass over the bulb and the reflectors absorb a lot of lumen, but it's fairly neglectible when you think of the fact that you can place them too about 1 foot above the plants.
It's true but the amount is very small compared to how much closer you can get the light to penetrate deeper into the plants. You win more then you loose it's all in the math.