LED's

[FishGeek]

I was wondering if there are any Electrical engineers out there? I need some advice on an idea I'm working on. I have a LED flash light which puts out a very bright and blue light and is only powered by 2 watch batteries. Also when I projected this light into my aquarium, it gave a shimmering effect like MH lighting. My question is about how many Ultra Brite LED's would be needed to give the same light output as say a 175w MH? I think this would be a great way to light aquariums in the future. The bulbs are cheap and cost next to nothing to power!!
Just would like some input on my Idea

Simon