That bulb puts out fairly low lumens for a 105 watt cf. Plus, at $55 per bulb, it's no steal.

Further, a 6' tall orchid case will require a lot more light to get adequate light to the bottom.

Thanks Homer,
Actually the price is for a 2-pack of the bulbs, so it isn't too bad. You really think that is low lumens for 105 watt? What would be considered normal for that many watts? If you have a link to a bulb that would be good for a 6' tall case, I would appreciate it.

-DH

At 6 feet, you would probably need a metal halide, especially if you are growing orchids and want them to bloom. The initial cost of a metal halide is greater, but it's not bad long-term, because you'd have only one bulb to replace, not the 10 (or more) fluorescents that you'd need for a tank that big. Just make sure you hang the light outside of the tank, have a cooling fan in the light fixture, and then additional cooling fans in the tank as well. In the summer it would get super-hot in there without any fans. Make sure you get the right spectrum of MH though. Some of them can be very red or orange, which not only looks bad, it's not that useful for plant growth.

Thanks for the reply. But I am getting a bit confused by all these lights now. The CFL bulb I posted above does nearly 7000 lumens at 6500k, where as the closest MH bulb I can find on topbulb.com is a 175 watt 5200k bulb at 12000 lumens for the same price as 2 CFL's. Wouldn't I be better off with 2 CFL's? The price is the same as one MH, the color temp is better, the lumens for 2 CFL's are equal to the MH, and they have a longer life span. The only 6500k MH bulbs I can find there are expensive and short lived. I feel like I am missing part of the equation here. Is there something else that should be factoring in?

-DH

http://www.topbulb.com/find/Product_Description.asp_Q_intProductID_E_45436

Okay, how about a compromise? :)

175w 5200k 12000 lumen MH. Will this get the job done for me? They do have a 175 watt 6500k, but it is $125 and I think that is insane. We ARE talking about a lightbulb afterall. What kind of a fixture is a bulb like this going to need and where can I get it?

-DH

Ok, I think you're overkilling here. Metal halide for a vivarium (even big one) will become a furnace. Your tank won't work with a single bulb, even with your 6720 lumens CF. It's like a spotlight. I would suggest a whole panel of twin tube CF's (maybe 12-16 bulbs) mounted on a highly reflective background. That should give you a much better illumination of the whole volume. Plus, you'll actually be able to afford the bulbs (initial investment is still steep but if you slowly replace them in a cycle of several months when they get older it won't hurt as much). 36-55W would be sufficient per bulb. Here are a few suggestions:

Compact Fluorescent PL55 watt Full Spectrum
or check out all the full spectrum CF's in their catalog:

Naturallighting.com CF's

or

CF-L36VLX - 36W CFL HAPPYLITE REPLACEMENT

Metal halides are better than fluorescents because the light can penetrate much farther. And in a tank as tall as yours, that's a good thing. However, hoschi is right, your tank will heat up a LOT if you use a metal halide. And after seeing your other thread, you won't actually need that much overhead lighting if you're putting your tank in your sunroom. I would suggest just enough lighting to clearly illuminate your tank so that you can enjoy your boa. So just go with cfl's, and do what hoschi suggested. I forgot that your tank was 5' wide! =) One or two compacts would not cut it. You could even go with normal VHO fluo's. Get four-foot tubes, a good reflector, and there you have it, nice, even lighting. The T5's are particularly good. T5 VHOs (very-high-output) put out more light than compacts, and are very sleek and slim in appearance.

Thats what a fan is for. I have had a 175 watt 5000k MH on my viv that is 3' tall and it does not heat up my tank at all. It sure doeas grow the moss on the substrate its like a lawn. My orchids and ferns love it also. You should check ebay for bulbs or aquarium supply. Or Hellolights I bought my 5000k from a local fish store new for $20 I also bought a coralife 5500k new for $25. I would go with halides for that size tank you wont regret it. I would go with at least 250 watt for that big of a tank. I just tonight put a 250 watt 6500k on my 3' tall vivarium dont think I like the color of it though. Look for Venture brand bulbs they seem to be inexpensive. Good luck

I ordered a fixture, ballast, bulb and socket already. It's a 250 watt setup with a 5200k bulb. I agree, I think it is the best way to go. Does most of the heat produced radiate off the bulb or carry with the light? I am not sure if I should put this in or out of my tank. I need the heat, but I would rather keep it out of the tank for safety reasons.

-DH

I believe the bulb produces the heat (as well as the ballast). Light always does carry some heat with it, but the bulb itself would heat your tank more than the light given off. I would still keep the bulb out of your tank though. You definitely don't want water to splash up and hit the bulb, making it explode, or your snake to touch it and fry himself. When you want the heat (in the winter), try using a screen top for your tank, to allow the heat in. This will also allow your UV light to be much more effective (as I'm sure you already know). It will be extra work to keep the humidity up with a screen top, but otherwise your tank will be too cold in that sunroom.

Yeah, I will likely leave it over the tank, but since the ballast is remote I might place that inside it. There will be plenty of safe places in there where it won't get wet. The UV bulb I haven't quite figured out what to do with. I may just locate that one inside the tank. I am trying to avoid using screen. It created a lot of problems for me on my existing setup. Thanks again sahoyaref, you always have the answers :)

-DH

Well I would hang the light. The 250 I put on my tank last night puts out alot more heat than my 175. So do to my closed canopy w/fan 250 gets to hot, oh well. I guess If it isnt broke dont fix it.