As stated PH is high. Im not sure what your issues are as Im a newb and run different system but at week 5 you should have a huge root ball IMO. Also plant is kinda stretchy, if not strain related it could be lighting as well. Here's some plants at 15 days from seed
. They are under 4 T5's and will move to a 600HPS in 5 days. ph is at 5.8 and running around 350-400 TDS. how often do u change water? And again as stated, IMO it is easier to run a sterile res when a newb for easier nute level maintenance, may get slammed for that lol. Good luck!