You just need to get your timing right when feeding your plants. Like if you're running HIDs water 2-3 times a day. CFLs 2 times. 1 water in the morning and another watering 1 hour before lights go off. And if it gets really hot in the room you may need to water more often.

with straight rockwool you gonna run into a lot of problems like this, you could use pots filled with hydroton to give the roots some breathing room.
nimo_253 Reviewed by nimo_253 on . Ebb and flow problem...why are my plants turning yellow? (merged) Can any one answer this...it seems pretty simple but cant seem to get anything in plant problems to match ...i keep having a problem when i switch from one growth stage to the next ...i had ak47 and burmese kush plants in 4x4x4 rock wool cubes which i watered daily by hand with a basic flora nova grow and hygrozyme nutriernt mix the plants flourished ..i did this for almost 7 weeks and was able to sex out the true males...i then took my remaining females and put those into a 4'x4' ebb and flow Rating: 5