Crazym88: as you can see there's a lot of difference of opinion on that. I run straight T-5 lamps, specifically: all 5,000K's for vegging and all 2,700K's for flowering. A friend mixes his but he relies on the change in photo period and diet to do the trick to flowering. I can't say that he's had any better luck with his grows than I have. Another friend adds an HPS lamp to his T-5's for flowering and I'd say the end result is pretty much the same. Two others are vegging under T-5's and one is flowering only under HPS and the other is using only MH for flowering. Their buds are tighter, denser, but frankly I don't think they taste as good as mine. Without some really careful testing I don't think we'll ever find out why. I think the difference might be the difference in our nutes. The important thing is that mine do the job of deadening my arthritic pain at a small fraction of the cost. And for what it's worth I haven't found combinations of lighting recommended by any of the sources I've consulted like: Cervantes, Rosenthal or Greg Green, unless I missed it. I hope that helps. HSA