It took almost two years for the nodules to start forming, but if they have nothing to do with pool chemistry, then it's highly possible the PB didn't do a proper plaster job. Is it safe to say that if chemistry was not the issue then the nodules will likely start popping up again?Shrinkage cracks can be caused by excess water and excess calcium chloride added to the plaster mix. They can also be caused by not protecting (tenting) the plaster finish in hot and dry weather before it fills with water. Delamination (bond failure) can also cause cracks and pinholes to form, and then nodules will generally appear soon. The formation of nodules have nothing to do with the balance of the pool water.