I have a 75g, currently a FOWLR, lit with one pair of 96W PC's. I want to upgrade the lights and go with more reef. I want to have the option of SPS, but it won't really be an SPS tank most likely.

I thought I had decided on 4 - 6 54W T5's (as seen here: http://www.reefgeek.com/products/cat...ng/104069.html or here http://coralreefbazaar.com/product_i...products_id=68 ) but it was recently suggested that I look at a set of VHO (as seen here: http://www.hellolights.com/4654lamvhore.html ).

Before anyone suggests MH, I like the shimmer effect of MH, like everyone else, but I'm concerned about heat and my hood not being tall enough, and I already have a ton of evaporation with just the single fan on my tank (and my chiller is sold, lol) so I don't want to do MH.

I've heard T5's have low heat production, but is it lower than with VHO, or with my current PC's? I think the answer is yes compared to PC's because my PC's get pretty hot, and when I was looking at some T5's on a tank in a LFS, you could hold your hand on them when they'd been on for hours. So what about heat with VHO's?

And what's all this I hear about PAR? Does that refer to having more of the "type" of light corals need, and does that have to do with the wavelength or water penetration (I know WL and pen. are related) or intensity or something else?

Oh, if anyone wants to suggest a specific good deal on lighting, I'm finding one of my major limiting factors is that the inside of my hood is exactly 47 1/8" wide and most of the 48" retrofit kits are slightly longer than that. I am most definitely open to any offers of used lights which fulfill my needs!