I am growing White widow and blueberry auto flowering that I got from 420. I have a 4ft yeild max ufo hydroponic grow box from unique hydroponics. My plants are 11-12 days old and they are starting to turn yellow. My pH is around 6.0-6.6. I have them on an 18 on and 6 hour off light schedule. I haven't given them any nutrients yet. What is going on and what can I do?????