First thing to do is mix up a lot of PH6 water and flush the plants. Then put in the nutrient mix you want to have and water right after flush. In coco, you want 5.5-6.5 with 6.0 being considered the standard to shoot for.
To answer your original question, I would expect to see leaves yellowing in between the leaf vanes, burnt edges on the leaves, drooping leaves, stalled growth.