whoa i just missed something while reading your problem!! your only irrigating for 10min every 12 hours??!?!?!?!?!? wow i think that is a huge problem! in veg i flood 8 times for 15 minutes and flower 4 times for 15 minutes!! so basicaly im flooding for 15 minutes every 4 hours. with your slabs i would ATLEAST flood 6 times a day for veg or 3 times for flowering. i am almost %100 positive your under flooding and thats the sole problem you have