Hey mscaboo. Dude, got a friend that owns a fertilizer company, they specialize in making it. He mixed me some that is 24-8-16, about 1/2 a gallon every 3 weeks. It's just over 2ft, in 3 gallon bucket. Using Scotts potting soil with added phosphorus for root growth. with a 500 watt HPS. It seems very healthy besides this problem. And it's only showing on a couple of leaves on the very top. It's been growing at around a 1/2 in. a day. I'm told that's pretty good. Please help dude?! I've got 2 other smaller ones coming up right behind this one. First time grower here, and my fiance won't let me put alot of money into it. Hey, gotta make the Woman happy. Appriciate any help. Thanks and keep on token!