I couldn't agree with Gainesville more, your buds aren't anywhere near ready to be chopped down. I wish I knew more about hydro and could give you some advice, but I grow primarily in soil, and don't want to lead you astray. If I saw that in my grow, I'd be thinking nutrient lockout or burn, pH issues, or salt buildup. But again, this may not apply to you at all.

Maybe we can get this thread moved over to the hydroponic section, or plant problems. It'll probably be noticed quicker by the hydro growers that way. In the meantime, I'd take it easy with the nutrients you're feeding until someone can get in here to compare notes and see what's going on. Good luck.