They're in net pots in an ebb & flow tray. I sprayed them with Nitrozeme, which usually works, but no luck this time. They have plenty of light and the fluid is good (3 part GH grow formula), temps and humidity are normal.
Only thing I can think of is maybe I'm over watering. Any recommendations on watering intervals? With rockwool, once/twice a day at this stage would work, but I'm a noobie with hydroton, which doesn't hold h2o like rockwool. Right now I'm flooding the tray every 2 hours when the lights are on and once during the dark cycle.
Also, how do you clean the root matter out of this stuff when you move onto your next cycle.
Any advice is greatly appreciated.