Are you using PoolMath?
A gallon of 12.5% in your 15,000 gallons will raise your FC by 8.3.
The recommended target in the startup guide is 3 ppm to not bleach the color out of your new plaster that is still curing.
I just went by the instructions on the label which said for new start-ups superchlorinate with 52-100 oz for each 10,000 gallons (15k gallon pool) so i did the full 128 oz since I have zero chlorine...did i just screw up big time???
I'm starting to think the PB didn't add any. The empty jug was just in a box of trash he left.