I have been looking at the compact fluorescent lighting available
(e.g.,from all-glass: www.all-glass.com) to replace my current
standard fluorescent setup.

Now correct me if I am wrong, but it looks to me that if you have a
48" tank, for example, and you have two 55 Watt compact fluorescent
bulbs -- one on each side of the divider -- then the combined wattage
(110 wattage) is not really what the plants are getting. Instead, it
seems, that each side of the tank will receive approximately 55 watts
+ some small additional wattage indirectly from the other side of the
tank.

This seems to be less than my current setup where I have two 48" 40
watt bulbs. Here both lights are on each side of the tank and, given
an even distribution of 40 watts eminating from the bulbs, each side
would receive a total of 80 watts; arguably higher than the compact
light alternative.

Is this scenario incorrect in some way or does it make sense ?

Homie wrote:
I have been looking at the compact fluorescent lighting available
(e.g.,from all-glass: www.all-glass.com) to replace my current
standard fluorescent setup.

Now correct me if I am wrong, but it looks to me that if you have a
48" tank, for example, and you have two 55 Watt compact fluorescent
bulbs -- one on each side of the divider -- then the combined wattage
(110 wattage) is not really what the plants are getting. Instead, it
seems, that each side of the tank will receive approximately 55 watts
+ some small additional wattage indirectly from the other side of the
tank.

This seems to be less than my current setup where I have two 48" 40
watt bulbs. Here both lights are on each side of the tank and, given
an even distribution of 40 watts eminating from the bulbs, each side
would receive a total of 80 watts; arguably higher than the compact
light alternative.

Is this scenario incorrect in some way or does it make sense ?

The below is assuming that you're 2 x 40 look something like
http://www.all-glass.com/products/ho...intube_img.gif (or two
single strip 40 watt bulbs).

I think you may be looking at the 40 Watts bulbs wrong. The way I see
it is that a 40 watt bulb is 40 watts over the entire thing so the left
has 20 watts and the right has 20 watts. So basically with two bulbs,
the left and right halves are getting only 40 watts each. This new
compact light will increase it to 55 per each side. (And if you want to
get all technical, I think that you lose even more light with your two
40s since, again, I'm assuming here, that your 55G tank has a divider in
the middle which is removing that width of light from the bulbs.
Assuming that the divider is 2 inches wide, it's 4% of your 48 inch
bulb. 4% of 40 watts is 1.6 watts x 2 bulbs = 3.2 watts lost because of
the divider. So in theory, you lost a couple of watts on the divider
alone on a 48 inch strip light.)

Rambling helps with boredom at work! :-)
-Ben