A MH light will work, but NOT AS GOOD as a HPS bulb. And that my friend is not any internet mumbo jumbo, that is a fact you can find anywhere,and any Novice grower should even know that. Like I said obviously it will work, But why waste your time with something that isnt as good?
you can rock what ever bulb. Its about spectrum and par. Hps lacks alot of deep red and UV that plants need. Mh has less yellow and green than hps . Anything higher than 20% intensity of yellow and green is wasted light and not absorbed by plants and lowers par.
Most mh have higher par than hps. But do lack in deep red 660nm like hps. Now that's fact . High Kelvin rated mh do produce more heat than hps though.
here is a study from oxford experimental botany department.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892149/
dusty keep up the good work. They look good. Don't listen to haters that don't know what they are talking about.
next run check out Philips all start cmh and Philips elite agro and gavita hps
I was rocking all start 330's and getting better results than 600 watt hps. Until they were stolen last month including plants and many other things
also with mh maybe supplement with some deep red or warm white leds. Cree globes from home depot work pretty well and are cheap and have a 10 year warranty. Also zoo med flora suns t5 bulbs are full spectrum and have deep red and uva and uvb like cmh
I've also been curious about solis tek 4k mh for flower too.
happy growing