HELP!!! Fan leaves starting to die?!!!

On the tips of my fan leaves, they're turning brown, almost like they are dying, but the rest of the leaf looks fine. This is happening with mostly all my fans. She's been growing for about 2.5 months, I have 4 17w(equivilant to 75w incandescent)fluorescent's on each corner of my growcab, and 1 125w incandescent spot grow over the top. I'm growing using soil with a 30-10-10 miracle gro fert. I've just noticed this starting about a week ago, and ever since then, almost all of my fan leaves tips have browned and become brittle. Oh! Please help me and my babies!!!!!!!

are you in veg stage?

get rid of the miracle grow and get some fox farm big bud. I used it one time and the plant looked great but the tast was harsh even afture I flushed it the last two weeks of budding. any way the brown tips are eather not enough air flow or a little to mutch fertlizer or bolth. if you can i put them in the bathroom for a steam bath "not to hot" and thay love it