leaves curling up and brown tips

Hey guys I have a problem. My plants get about 8+ hours of sun per day. The bottom leaves are turning yellow and dying, and the top leaves are curled up and brown tips. I havent nuted in 3 weeks, so it is nearly impossible to be nute burn. They are in black pots that are also out in the sun. Please diagnose this problem, just click on my sig to go to my grow journal. (I am at work and cannot upload the pictures.)

Edit: I forgot to add, they have nearly stopped growing, though only one is currently flowering.

same problemo here lol