MH light distribution over 36" tank?

[Dazureus]

Hello, and sorry if this question has been asked before.

I have a 50 Gallon breeder with thoughts of upgrading sometime in the future (naturally) to a 65 then 220. The 50 gallon is 36x18x18. I've had it set up for three years now using three 95 W VHO's with some soft, LPS, and two SPS. Everything is doing fine, but I would like some more confidence with keeping SPS and perhaps clams so I was thinking about metal halides. I've done my research and thinking forward, I was considering a single 400 W in a DIY canopy. Reading Sanjay Joshi's analysis on light distribution and reflectors got me thinking. From his analysis, there will be very little light at the left and right 3 inches of my tank. Is there anyone that has a 36" tank and a single MH that can verify this for me. I'll probably elevate the lamp at least 8 inches, but does anyone have any suggestions? Thanks for your time.

[kevinpo]

IME for a 18" deep tank a 250W bulb is plenty and will help reduce heat and electricity consumption. A halide bulb will cover about a 24"x24" area. The higher you raise the light the more area it will cover but the less intense it will be. You will still have plenty of light at both ends, just not enough for high light loving Acropora species.

Regards,
Kevin
PS: A 36" long reflector will help to spread the light more than a 24" reflector. I have both and have seen the results on a 4' long tank.