Doug, that isn't always the case. I have an acro that colors up better for me when it is on the sand as opposed to up high. Different light will change the appearance, but not always for the better.
As for growth, I'm sure the increase isn't linear, but more light does equal more growth. I know this from experience. I've also taken stuff from my tank and put it under 400w Iwasakis, and the growth increased even more over what I had under my 10k bulbs.
So all else being equal, more light will give more growth in most cases. Or maybe I just got the super duper 400w bulbs!
