Here's an update for anyone interested...
I had my water tested at Leslie's for metals. The test showed that there is no metal in my water, though I do wonder if the sequestrant added to the pool has masked the metals.
My PB came out to look at the plaster and said that there was some "normal" mottling, but that the very dark blotches may be "trowel marks". The PB used a diamond sanding pad (on a pole) to sand down the darker spots in the pool. It appears to have worked because the spots have lightened significantly. My pool is 2 weeks old and it appears that the appearance of new "mottling" has slowed or stopped. My understanding is that plaster can take a month to fully set. I am hoping that I'm almost out of the woods and that no additional spotting appears. At least now I know how to fit it!
I had my water tested at Leslie's for metals. The test showed that there is no metal in my water, though I do wonder if the sequestrant added to the pool has masked the metals.
My PB came out to look at the plaster and said that there was some "normal" mottling, but that the very dark blotches may be "trowel marks". The PB used a diamond sanding pad (on a pole) to sand down the darker spots in the pool. It appears to have worked because the spots have lightened significantly. My pool is 2 weeks old and it appears that the appearance of new "mottling" has slowed or stopped. My understanding is that plaster can take a month to fully set. I am hoping that I'm almost out of the woods and that no additional spotting appears. At least now I know how to fit it!