Lighting is currently provided by 4 110 Watt VHO's powered by an IceCap 660. This setup will soon change as I have just ordered 2 96 watt DIY PC retrofit kits from Reeffanatic.com along with 2 36" polished aluminum reflectors and 2 72" 160 watt URI 50/50's.
So lets do the math on this shall we?
Old setup 4 X 110 = 440 / 125 = 3.52 watts / gallon

New setup 160 X 2 = 320 96 X 4 = 384. 320 + 384 = 704. 704 / 125 = 5.63 watts / gallon

I know the question is coming. Why give up 440 watts with the 4 110's and go with the lesser 320 watts.
Here's the answer to that:
there are 2 main reasons that I chose to do this. 1. The bulbs needed to be replaced anyway. 2. With 48" tubes, they did not extend fully across a 72" tank. Although they are staggered so at least the end of 2 bulbs make it to the ends, the dimming effect on the edges is very noticeable. Plus this will make it much easier to get the reflectors installed and make the wiring all neat and tidy.

So, the lighting will be setup like this:

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Bulb 1 |-----------------72" 50/50---------------------------|
Bulb 2 & 3 |----- 96W 7100K--|-- 96W 10,000K -------|
Bulb 4 & 5 |------96W 10,000K--|--96W 7100K --------|
Bulb 6 |-----------------72" 50/50---------------------------|
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Timer setting will have the 2 7100K's coming on first. This I know. Now I have not made up my mind whether or not I am going to have the 10,000K's and the 50/50's come on at the same time, or to have them on 3 different timer setting. If the latter is to be done, I will probably have the 50 / 50's come on second then the 10,000k's come on last.