Everything sort of hinges on the color temp. of the halides you go with... 6500-10000K halides I'd suggest running the 460nm blue T5s.. 14000K the 420nm or a combination of them work well, anything above 14K and your tank may really need white. It really depends on the manufacturer and where they are made the color temps will vary greatly for the same labeling. For example the the Japaneese made 23000K bulbs are more similar to the 14K US.

The idea of running the halides for part of the photoperiod... *most* tend to bring the actinics up for an hour or so before the halides come on let them all run for the desired time and then the halides go off leaving the actinics on for another hour or two before the tank goes dark.

Halide photoperiods for most tend to be shorter than with power compact lighting, there is a set amount of time where the animals have absorbed as much light as possible in a given period of time, beyond that it's wasted electricity and/or food for nusiance algae. This debate can get rather deep quickly, and there are dozens of variations.