Which brings us back to the big question. How many does one need to cover a 18" x 60" area?(which is roughly my rock area)

Thats exactly the area I'm covering with 3 sols 12" above water

Well assuming you run them lengthwise and set them high enough to cover the 18" width then you could assume they would cover at least 24" lengthwise being that they are 6" longer than wide. So 3 is what I would start with but I'd use the 70/70 versions.

What have you got for coral? Mine is heavily stocked SPS which really love the light. After 6 months with the 400w radiums, some will start to brown out.
I'm not sure 3 of these will replace what I have now.

Yeah it's hard to say, you might want to stick with the AI recommendations and go with 5 mounted the other way. The good thing you could always try 3 and see how it goes, if you find yourself running them close to 100% and still not giving the corals enough light you could always add the other two. IMO though if the 3 sols won't work then 3 Radions won't either.

Ya, I think they're fairly comparable, intensity and coverage wise. Problem is I can't afford 5, so if 3 didn't work, I'm stuck.
I guess until I see a colorful SPS tank running 3, I can't consider this.

Yeah although it would be cool to see 200W of LED replace 1200W of halide it does seem unlikely.

http://i562.photobucket.com/albums/s...d/69098bf1.jpg

those are with light @ 40%, and I will get alot better coverage if I have they mounted length wise across the tank.

I've got sps growing 18 inches deep no problem.

100% on both blue and 75% white and 100% only white when I'm at work

Look at dez's tank. He's got 3 covering a 60" tank full of sps