A halogen may work but it is in the daylight spectrum and you may get more algae growth than you want. I do know a guy that uses a halogen light that has the little 20w bulbs and T5HO lights. the little halogen lights are used to brighten the tank for viewing not for penetration anything. You do get a nice shimmer effect and the T5's get the penetration so in a combination I would think it would work out, I'd be ready for a algae bloom. I have never tried it my self you can also get little blue halogen bulbs that maybe good for moon lights.

Bill