vegging for 12 weeks? kind of pointless with a 400 watter as it doesnt penetrate very deep when the plants get tall. also a 400w only covers a MAX. 4x4 area. and 10 plants will be way to crowded in there after vegging that long. if your doing 10 plants with 4oow its best to keep em' shorter (SOG). you will have lots more quality dense buds instead of lots of airy fluff bud. and you can crank out 2 sog's in the time its taking you now.