Looks great! Just wait til it hits it's spurt. Should be 12 by week 4. I've got mine on 24/0 but 18/6 will work fine I think. Check out my AF Grow post and pictures. There's some useful info there for you if you need.
Im growing the same thing and also cannot wait try it. THC levels are around 18, 19, if its grown right. This is my first auto grow and I gotta say, its not my favorite way of growing thats for sure, but it should come out okay. Im also growing white widow auto and that plant gave me more trouble than anyother plant ever did. very pickey plant., but its cming around now. So Good Luck!!!
