Halide bulbs in parallel or series?

[Lampshade]

I run only 2 halides on my 6' with them parallel, I get great coverage(still should add a third though). Sanjay did a write up that shows the retrofit batwing style reflectors with a long narrow focal point, so if that's what you're running, you might even end up better off. The PFO Parallel reflectors where the closest I could find to the generic ones that most people run.

http://www.advancedaquarist.com/2003/3/aafeature