To begin with Robb, there is absolutely no need for MH on a small nano. I have run nanos for quite some time, and have never used anything but PC lighting.
At the present time I have a converted 11G Tropiquarium 55. The original owner converted the top to hold 2X28W PC's. (I will be combining my 20G high tank and that 11G nano into a 33G cube at the end of this week, so some things will be for sale) That was a shameless plug.. That system also uses a Fluval 204 to provide circulation.
Some folks also use old incandescent tops and use screw in PC bulbs which are self ballasted, and a nice option.
