For growing in soil your ph is low.....it shoud go in and come out between 6.2-6.8 for soil. Edit: I see you are in coco so forget that last remark.

I also remember Stinky talking about those grow bags and saying they are not meant to be be moved around......it breaks the grip between the soil and the root because the bag itself is flimsy and not solid. You are supposed to set them somewhere and not move them around. That may be part of your problem as well.