Metal Halide Lighting question

[jcasisa]

I am leaning more and more on using metal halide for my tank build, actually a MH and T5 HO combo and I was wondering the correct length for the fixture. If the light needs to be 6" to 8" above the water, do you want the fixture to me the full length of the tank? I would think a 36" fixture would be the correct size for a 48" tank.

Am I overthinking this?

-John

[Gig 'em @ NDstructible]

I would have the T5's stretch the entire length of the tank. The MH's can be spaced out a little bit more depending on the reflector since the light will disperse more from the reflector outwards. I would suggest 48" T5 lights and 3 MH pendants

[Gig 'em @ NDstructible]

This of course is assuming you're going for high light to grow corals. You don't want to leave too many dark spots in the tank by going short on lighting. It'll cast weird shadows in the tank and you will be limited to where you can place your corals. If it's a fish only tank or low light soft corals, 48" T5's would probably suffice.

[jestep]

You're most likely going to want 2 x 250 for a 48" tank, anywhere from about 36 to full length would be fine.

I used a 36" fixture on a 90 gallon - 48 x 18 footprint, and it had no problem lighting the tank. I used a single 36" reefbrite actinic LED strip for my supplemental lighting which was more than enough by itself as well. I screwed the LED strip into my hanging MH fixture.