Plant doing horrible and brown leaves w/pics

What should i do? I have the plant in a bubbleponics system and have it about 2-3 inches away from a cfl light on a 24 hour cycle, and water it about 3 times a day with grow nutrients. The ends of the leaves are turning completely brown and it is not growing, but the top still looks a pretty good green but with some of the edges brown also.

Are the roots getting enough oxygen? Have you check out the airstones since you set the system up?