If the leaves are curling and turning purple, you have a nutrient problem. How is your Ph? If it is out of whack, you could be in nute lockout. Try a good flush with plain water, and then check your Ph again. Once it gets back to normal, you should see a change in your plant. Once its back to normal, start adding nutes again at 1/4 or 1/2 strength and continue to observe.
i think purple leaves + curling is probably over-feeding....specifically, probably too much phosphorus (gives a reddish purple color) the curling will be from the P as well as too much water, if you are feeding too often