Thanks everybody for the great response. I think I'm going to start building a new light for my next tank so this info will serve me well. Since I've got the ballast I'll go with the double ended 250, probably aqualine and 2 65 watt actinic PC's. I think that would be a good combo of light and color. The tank will be 36" L, 24" or less high, and 24" wide. I'm trying to minimize lighting costs, electricity bills, all that stuff. It looks like I'll only be running about 4-5 watts per gallon, but the lights will be very close to the surface of the water, and there will be a 3" sand bed. I'll be keeping SPS and clams only. Also the majority of corals will be towards the middle of the tank. I guess I'm stretching it a little too thin. It's the length that is making the difference, otherwise I think there will be plenty of light for the middle 24" of the tank, with the last 6" on each side being a little thin, but having the PC's staggered to reach both ends of the tank. What do you guys think? Trying to maximize light while not running more than 1 250 watt MH...since I already have the ballast. Any other ideas? Thanks everybody