The plants look like vegetative phase II is starting, so I've added PK 13/14 to the nutrient solution this week. I have also replaced the light hangers and got the distance back to around 20-40cm. The CBD's leaves are curled up quite badly up top, but there isn't much I can do at this point. The other 2 tall plants don't seem to struggle as much with the light, at least judging by the leaves. The tall ones all have some burnt tips up top, which I assume is also partly related to the light - and maybe the clogging related dryback we had last week.
For now everything seems to be back on track. I expect the plants to take at least another 3-5 weeks.