Have you measured the ph and ppm of your runoff? If not....please do and post.

What kind of water are you using? You may be one of those whose water should be RO or distilled and some CalMag.

I'm guessing its either a ph/rockwool issue or your water. Good luck.
Weedhound Reviewed by Weedhound on . Newbie needing help please 4week old plant!! Hi this is the first grow ive ever attempted!! I bought 5 feminised cheese seeds from greenhouse seeds but only decided to germ 1 incase any major problems occured it wouldnt be a total waste. Conditions = Indoor Tent 80cmx80cm 160cm tall. 400w grolux dual spectrum cooltube about 97 cm from plant top. No extraction fitted yet but will have one next week atm just using a clip on fan pointing at light, pushing air through top of zip flap! Natural intake through bottom vents. Temp Day 24-27 Rating: 5