Planted Tank Guru
Join Date: Jul 2008
Location: East Lansing, MI, USA
I use twenty four 3 watt LED emitters running at 670 mA on my 75g tank. It's about four inches off the tank and probably ought to be a couple inches higher as it's a bit bright. Plant growth has been excellent.
A dozen Cree emitters running at 1 amp, mounted to a 48" aluminum "yard stick" would probably suit your needs. I suggest spending the extra $10 or so for a dimming driver.
There is a thread on here somewhere that covers that. I've spent ten minutes looking for it though, with no success.