The plants look pretty darn good, I noticed you are growing in a 5 gal Bucket.......I would make sure you have excellent drainage to enable better flushing. The soil level seems low for the size of the plant and would bet the roots are up against the hot plastic bucket. Might want to get some more soil around those roots. If ever in doubt about PH lock.....flush the buggars good.
Your plants thats are streching faster than others I would bet to be males. Keep us posted and keep up the good work.