mrg02d
Aquarium Advice FINatic
http://ledsupply.com/docs/cree-xre.pdf
There is some more technical data there, The whites are typically 90 and the blues 100. Post up your diagram if you make one, it would be a good learning visual.
EDIT: Don't forget to take into account the refraction when it enters the water and how high off the water they will be. Thats going to be the hard part
I did a quick sketch and found that the light ought to have no trouble at all filling the tank. Each LED is going to fill the tank by itself from a height of 7in.
I figured 100degress, thats 50deg for each side of the tank. 7tan(50) gives me a little more than 8in. That makes for a 16in diamter circle on the bottom. My tank is only 12in long by 6in wide.
Now I need to make sure the PAR is good enough...
Matt