MH and HPS mix

I have a 400w ballast being gifted to me :jointsmile: I have an existing 250w digital hps ballast (which through an unsucessful test I now know does not burn mh bulbs). I am setting up an 8-12 plant SoG in a 2'8"x2'8"x6' tent. I will obviosly have to use conversion bulbs for the digital ballast, and I don't know what kind of ballast the 400w is. That being said... I was wondering what would be the best mix? 400w mh for first 2 weeks, then add in the 250w hps, then vice versa for late flowering? Help! :beatdeadhorse: Also I have a few strains to pick from...any suggestions? Bubba OG, Master Kush, OG Kush, Alaskan Thunder fuck...i can't remember any more atm. Thanks for the help all.

Just use all of your lights for all of flowering.

yup