If the tank is 48" long and 24" high how far apart should MH bulbs be mounted in the canopy? Assuming I want to keep most any hard coral or maybe even a clam, how does two 250W MHs and two 96W PCs or 110W VHOs sound? Too much? Too little? What's your favorite source for retro light kits?
At 20-24" of depth, 250W metal halides are good for about four square feet. If the tank has a footprint of 48" x 24" then you're right where you want to be. A lot of folks space the bulbs evenly apart and I think just as many put them a little closer together, and then put high light stuff between them, lower light on the outside.
