Metal Halide Lighting

I recently upgraded my 30 gallon tank to a 48 inch long x 21 inch tall x 18 inch deep 70 gallon or so. The tank came used with a 2x250 watt metal halide and 4x65 watt power compact hood. (Pc's include 2x 65w 10,000k and 2x 65w actinics).
My question is how long should I be running the mh's and pc's for? In other words, what would be a good lighting program? For example, pc's for so long and then mh's in unison with pc' for so long. I would like to keep my energy bill somewhat down and refrain from needing a nuclear power plant to run my house so I would prefer not to run the halides the whole day.
Also, is this too much hood for my tank? The distance from sand bed to fixture is about 21 3/4 inches and I do plan to keep sps in the future.
Also,does anyone know what it cost to power these duel 250w mini suns for any given amount of time?

 

pcs 12 hours a day..and halides around 8-9...

but make sure you acclimate your corals with that fixture