Plants are 2 weeks old, I have thought they are struggling from very beginning, maybe thats the strain. Its a DWC grow, white widow, in a 8 x 4 x 6 ft tall grow box. intake fan, bigger room exhaust fan, big oscilating fan inside, right now 400w mh at about 2 ft away. temps from 80 - 74. humidity 55. ph at around 6 although it does go up fast by the next day its 6.7 ish. 8 of the 10 now have roots out bottom of net pots, the other 2 I help by watering 4 times a day while lights are on, on 18-6 now. I have thought for a long time now that they are going slow but since they started to get their roots going they r getting bigger now. problem is they look very yellow rather than green. and for a while now I saw that their leaves were looking brown and crispy at ends. Thay are all getting worse. the first pic is my biggest and healthiest and it is now getting the prob with leaves, the second pic is one of the plants without tap roots through net pot yet and is the smallest and in worst condition its leaf ends are brown and withered. please help im gonna lose these little ones soon. started nutes last night at about 600 ppm, but these probs were very aparent b4 the nutes were added. anyone help, thanks...