What strain is it?
It's definitely magnesium deficiency however I also think it's due to a lack of Nitrogen. What are you feeding them and how strong? Substrate looks to be coco. Yes?
looks hungry as hell. Feed her
I bought them as preteens so I flushed them and started going them sensi grow A+B and se rhino skin. I stopped giving them nuts and flushed them a few days ago when I saw these problems.
The sensi doesn't have enough calcium or magnesium to satisfy the coco. You need ca/mg in addition to the base.
Use b52 its made from calcium and magnesium nitrate
