I believe its your ph... ingoing ph for hydro should be 5.5ish.

however, if you do switch to soil the ph should be about 6.5.
Faddenator Reviewed by Faddenator on . Leaves curling up on edges, drooping and black spots Hey all. I recently switched to 6" rockwool from coco in previous grows. i had been using tap water corrected to 6.3 ph. the serrated edges of the fan leaves started to curl up and over. i called the hydro shop and they told me to use RO water and suggested i might be over watering. i let the rockwool dry out and get nice and light then watered with RO water corrected to 6.3 ph and 1000 ppm combined botanicare pro grow, Cal Mag and liquid karma. the leaves are still curling and now some Rating: 5