Maybe worth trying something with oxygen,you said low bubbles and big rootball and airstone. imo They look overwatered. First time I heard that I asked how can that be with dwc.It was explained in several ways. One guy said the airstones were just somewhere to get clogged up & to put a stainless screw in the end & adjust it. I haven't tried it yet right now I'm trying with just hose.Yours looking good other than that, & I'm no expert. I know from experience I can water more if I give more oxygen. A clean bucket is good always.
I like to defoliate some,looks like to me - to much slows growth, them big leaves help the speed of growth,but they block a lot of light,so I try to take the ones that are blocking light only. I been throwing them away,but I see trichromes on these and I think some peep make something out of them.Good Growing All.Peace