The Plants are doing great this week.
BBM1 started to swell noticable over the past days, so I guess she is recovering.
BBM2 and 3 are stacking budmass fast.
Slowly increased nutrients to full dose now.
Watering with 5.8-6.0 ph and an 2000 EC around 0,7-1l per 3 days with no drain at all.
PPFD lightly increased to 850-900 @ tops.
I don't believe your soil is depleted. Roots cant absorb the nutrients that are there when moisture levels aren't correct/ theres not enough dry out. The small root hairs begin to rot when the average moisture is too high. You might have to slightly adjust your watering amount to less, or adjust the time between waterings.. Thats my 2 cents based off what I see