Cliff - I'm going with 250watt electronic ballasted halides. I purchased 5 retro kits as I thought 4 might be alittle weak, especially after being used to my 400watt halides on my 75g. I know there has been a lot of praise for the 14k Hamiltons, but I will probably stay with the 10k XM bulbs for now. I was thinking of supplementing with T5 actinics, but I've heard mixed reviews on those bulbs so I may just reuse my VHO ballast.