if anyone on here has seen my duncan colony before i chopped it up... thats how i bought it like 3 or 4 years ago (on the sand, left side). i think it was 4 or 5 heads when I got it. ive probably grown a soccer ball size amount of them since that tank. lol
if you go for LED then do some research first and make sure they are adequate for the depth of tank you have. There are some £600 units out there which are no good for my depth of tank.
They seem to be like fish too.........what works great in your mates tank may not behave the same in yours. (my LFS have used the supposed market leaders and best but had worst results than the ones he changed to which us older technology!)
I have a DIY. 24" Heatsink. Over my 40b. 36" wide tank. Two groups of LEDs on the Heatsink. About an 8" gap between them. I have 225 par on my sandbed. Cost me about $550.