Keep a close eye on the leaf tips my friend...at that distance there seems to be some browning taking place. Not sure what the exact cause is, but be sure the plants have good clearance from the fans blowing out the ends of that unit. It gets rather hot. I think its causing issues, but not sure. the tips are curled, new growth is browning, the leaf is falling off (fan leaves). Big problems on this end.... not sure what though. not saying its the light, but keep close eyes at that distance, i think its closer on this end, so 12" should be good. Hows the coverage?
Looking good my friendly friend!!
-pf-