I'm getting ready to put a few plants into flowering and was wondering about lighting. I plan on using a 400w HPS but I also have a switchable 250w. Should I run both HPS or the 400w as HPS and the 250w as MH?
Depends how you have your lights and plants arranged. if you are trying to light a broader area by using two lights then go HPS with both. If you are trying to add light intensity and broader spectrum to the same area as covered by the 400w HPS then I recommend running MH in the 250w, though even in that circumstance running more HPS is a good choice. What you don't want is HPS shining here and MH shining there, that's not mixed spectrum because some plants are getting one while other plants are getting the other.
Right on toasty, I knew I could count on you for a great explanation and insight on this. Thank you for the answer and your time.