Yah we had the purple stem thing going on...but I hit them with some 5-1-1 fish emulsion and waited a few...they got greener then the bottom leaves started to get really yellow and I just went off...!!!! I did an emergency wash-out and then used a mild epsom salt coctail on all my babies. The yellowing stopped almost immediately, and so now I'm holding my breath. NLxBB, and some God's Treat under 400watt HPS. This is all taking place at about seven weeks veg and the light is now on 12-12, just gotta keep um small enough to manage. All seems well for now. I plan on using Fox Farm Big Bloom half strength for a while and playing them some nice tunes...ha ha!!