2nd grow with updated grow room

Everything is going smoothly, they are growing really fast and I am now struggling with LST so I will stop it when they flower. I accidentally broke the main stem of GC#2 few days ago but she is already recovering. I watered with 2,5L for each today and there's still no runoff so idk if I should give them more next time because I'm afraid of salt built-up if some water don't come out of the pot. I will probably flush them with plain water at some point anyway just to be sure. Watering for this week 04/04: 2L at 6,4pH (with last week's nutes) 07/04: 2L at 6,3pH