200 gallon reef tank metal halide help!

[Aquattro]

That's a deeper tank, I'd go with 3 x 400w. color temp is simply your personal preference. 10k are whiter and brighter than 20k, but white to the point of almost yellow, depending on bulb. Radiums are really nice blue, but less intense and need replacing every 9 months (ideally).
A nice compromise might be a 14k bulb.
Keep in mind reflectors can make or break your bulb choice.

[Skimmerking]

or go with 3 250's and used Iwasaki bulbs and use VHO Actinic's

[Aquattro]

Originally Posted by asmodeus

or go with 3 250's and used Iwasaki bulbs and use VHO Actinic's

While those bulbs would give you more growth than any other bulb, IMO it's the crappiest look I've seen on a reef, and doesn't bring out the colors typically sought by people for display tanks. And once you factor in the amount of actinics to get it less fugly, you might as well go with the 400s at the color you like.
Iwasaki is a great frag grow out bulb, but not a nice looking color.

[Lance]

I agree with Brad. 3x 400W in a 14 or 15 K would be my choice.

[staceyd72]

For a 36-38" tall tank you most likely will want 400W, maybe supplement with T5 or VHO, as mentioned colour temp is a personal choice. I find growth and colour is good with a 14K bulb.
I have a 250G with 2 400W(used to be 3) at 28" tall in Lumenarc (large) reflectors and supplement with four 165w 454VHOs, works for me.

I use 'sakis(6500K) on the frag tank, ugly to look at but grows coral like weeds
Back in the day we used to use the 'sakis on the DT, with the proper Eye ballast they actually look very nice.