I am a first time grower and I am experiencing some problems. I have 8 plants growing in 5 gallon pails under a 600 W Super HPS lamp. I am using DM nutrients, (part A & B and Add.27). PH is between 5.6 and 5.8 and EC is between 1.5 and 1.6... Plants are in their 6th week of flower and up until 3 weeks ago, everything was going just fine. Then I noticed tips of leaves yellowing. It has gotten progressively worse since then. Can anyone out there tell me what the hell went wrong?