ive been looking through your diary . First thing i saw your temperatures are pretty high, Weed likes it under 28 degree, best temps are between 22 and 26 degree, thats the wellnesstemperature for weed. And your rh was not optimal way to low. Weed likes it more humid in the beginning, they grow much better. And i think your composttea was very rich in nitrogen ( can see it in dakgreen leaves and burnt tips) It may be the combiation of enrichd soil and composttea too.
. After plant has stopped stretching there is no need for nitrogen, choose another composttea with P and K. The purpel stems anre genetics , nothing to worry about.