It looks like your using
led lights. If I remember correctly, leaves curling is fairly common with them, and just normal with LED lighting. Another thing that stands out to me is that you mention your using General Hydroponics (GH) gro for
nutrients. I assume your referring to the general Hydroponics Flora series. That's a 3 part
nutrient solution, it needs all 3 parts (Gro, Micro, and Bloom) to be able to provide all the mineral elements. The ratio of how much of each are added to the nutrient solution depends on the type, and needs of the plant.