In article , says...
... I built a house 2 1/2 years ago and I installed recessed lights with Elzak
reflectors. The bulbs are 23W, supposedly equal to 100W incandescent, with
1600 Lumens. I am more than pleased. This experience is what caused me to
ponder the question in regards to reef lighting. In essence, does the same
hold true...at that rate, a single 96W CF tube would equal 417W of
incandescent lighting and 667,826 Lumens.

There is an error in the decimal point, it should come out to 6678 lumens.


I have no experience with MH, and
have no idea how it compares...so, is there any reason a person
couldn't/shouldn't use say, 500W of presumably cooler-running CF instead of
500W of MH? Would 300W of CF equal 500W of MH, or would 500W of MH equal
1500W of CF, for example?

MH is about as efficient as fluorescent in terms of light output for a given
electrical input. It has the advantage of being more compact for a given power
level, so you can fit more over an aquarium if you so desire. The downside is that
these expensive lamps degrade faster, causing the light output to fall off.
Fluorescent is best in that regard, whether it is a standard T8, a T5, or a power
compact.

In practice one can buy a sleek 48" power compact fixture with 4x96W 50-50 lamps
from one of the better companies, like Coralife. It will produce _plenty_ of light
over any popular 4 foot tank like a 55, 75 or 90G.