Thanks PF! I will have to try that next round.Lookin good. Here's a tip that works for me.
If I want more growth, I simply increase ppms to ~ >550 at same light schedule.
Apparently, the increase in PK signals the plant that it's time to flower. It takes ~ 10 days to see early pistils and clusters developing (much like your pics), THEN I begin to lower the light schedule
hth