would this light be ok?
 

Would this light be ok to use on my 5.5 desktop nano? Would I have to worry about sitting next to it all time because its a metal halide.
Aquarium Lighting for Nano Reef Aquariums: Viper HQI Metal Halide Clamp Lamp

That should be more then enough for the tank. You could keep most any SPS accept for the low light SPS perhaps... not sure though, but it'll be enough. You will only need to get the 70W fixture. It may be a lot so you could raise it high off the tank and use a small computer fan to blow the air accross the top. That'll bring the temp down by a few degrees. I also have a 2.5g Picotope tank that's being run with a 10w Power Compact 50/50bulb. everything is going well and keeping some of it's color. It's in my signature if you want to check it out.

Happy Reefing.

That is a very good light for a 5.5. I have seen that light used on 3G and 2.5s and they look amazing. Just be careful about heat/evap.

I have a 5 gallon which the light doesnt work anymore and the switch is broke too. so I use a reading lamp. and the fish get plenty of light and warmth from it. I thought this would have to work, since Im not going to go out and spend a ton of money on another tank, .. the fish are happy..

This is in the reefing subforum. A reading light that is incandescent will never work.

I whole heartedly agree with Cody. There's no way this will work for soft corals let alone SPS.

How hot do halides get? I've only had PCs before. It'll be on my desktop. Will I be bothered by it?

probably. If you blow the fan away from you, you shouldn't really feel anything, but go to a local LFS, they should be using MH in at least one of their tanks, or display tanks, and just put your hand close to it. That'll give you an idea of what you'll be dealing with.

Very hot. You will most likely have heat problems and a lot of evap.

To solve heat: Get a lot of fans, or better yet, a chiller.
To solve evap: Glass top. But, this keeps in heat, which basically means you need to get fans/chiller.

When you put the fan on the tank face it down at the water it helps alot. I run over a 1000 watts on my 125 reef tank. When i first put my fans on 2 in and 2 out i put them just blowing at the lights my tank would still run about 81,82 at the peek time. But now i have them facing the water it keeps it right around 79 to 80 at peek time.Good luck and happy reef keeping