There are 2 main types of lighting: high intensity discharge(
HID) and the fluorescent(
VHO,
PC,T5).
Equivalent wattage fixtures: 250wt
HID vs 250wt Fluro
1) will consume the same amount of electricity
2)
HID will penetrate much deeper into the tank
3) fluro wins the battle for evenly dispersed light throughout the tank
4) they will both put out a good amount of heat
Now, I haven't had time to fine tune the maths, but replacing bulbs also becomes a factor:
Six 40 watt
PC 50/50 bulbs = $120
One 250 watt 14k
MH = $57
(prices from Captivereefs)
Tosum it up, it all depends on your tank parameters (size/depth). Ideally a mix of both types should be sought nice dawn to dusk effect). Many people will tell you that you can't have this or that in your tank unless you have
MH (not true -- have seen some incredible tanks using only fluro lighting).
As for the most bang for your buck (
PC vs T5 vs
VHO), I don't really have answer.
I'm guessing that T5 wins out with regards to:
1. light output per watt
2. more balanced PAR spectrum
3. unobtrussiveness of bulb/fitting
I may be misled on some of this (am by no means an expert), please let me know
cheers
nick