Floro tubes are much easier on seedlings for the first 1-3 weeks.
Metal Halide bulbs puts out a lot of UV light, which is hard on seedlings. You have to place the MH bulb very high up and you need to monitor it constantly, watching for light burn.

You have a choice of veg light times; 18/6...20/4...or 24/0....whatever suits you best.
Flowering is 12/12.

p.s....don't put seedlings directly under MH....offset some.