Light "Penetration"

> From: Cliff Andrews <CLAndrews at gnn_com>
>  I've added a new wooden canopy to my 100 gallon planted tank and instead of 
> using the four 48" fluorescents I had hanging above the tank, I'm thinking 
> about using all compact fluoresents inside the hood. I want to have better 
> penetration of light to the bottom of the tank and the nice effect that 
> comes with high intenity lighting. My aquarium is 20" deep. I dont want to 
> go as far as MH lighting, I think that is over kill. I was planing on using 
> PowerCompact 6700K Ultra-Daylight bulbs, how many ? 

Umm, light is light.  There is no type of light that has better
"penetration" than another, unless you're talking about the attenuation of
different colors (which isn't going to be an issue at 20" anyway).  What
you want is "more", not "better penetrating".

> I have been playing around with one small compact fluoresent unit I have. 
> Its has two OSRAM 9w 50K bulbs in it. I did notice that a small amount of 
> alge will grow in the gravel below it, good light penetration huh?

Power Compacts are not the same as the small 9W and 13W compact
fluorescent tubes.  The former are high-efficiency, high-wattage,
ultra-high cost bulbs, while the latter are the same efficiency as normal
fluorescent tubes.  Their only advantage is being able to put a relatively
large amount of light in a small space.  For a 100-gallon tank, the area
is large enough that you just need high intensity, distributed about the
entire tank. Period. Use MH, use T-8's, use power compacts, use VHO, use
10 old-style fluorescent tubes packed in together.  Just depends on the
amount of money you want to spend.  Each produces light.  Each

(Of course, my money is on the T-8's for best value.) :)

     - Erik

Erik D. Olson					         amazingly, at home
eriko at wrq_com