Questions regarding Cree LEDs ??

[reefwars]

Hey I'm curious on how much space the Cree 3w LEDs light up??

I want to use them as lighting before and after my halides are on ,my tank is 20h but it's quite wide any advice would do

I want to use 6x3w LEDs between each of my four halides?? Tank is 48x48x20high thanks in advance:)

[sphelps]

Correct me if I'm wrong but I believe without optics the spread is 120 degrees. With optics it's simply the angle specified, the largest I think is 80 degrees and it goes down from there. The greater the angle the less penetration you get, for what you're doing the 80 degree optics may be a good choice.

[hillbillyreefer]

http://www.reefledlights.com/how-to-diy-led/led-faqs-questions/

1, 3w led per 12-15 sq inches of surface area. #21 on the FAQ page listed above.
I think I learned more about setting up systems on that site this morning than I have in the last 6 months of fumbling around.