Hello,
There was a bad batch that had high alkalinity. You should return it and get a refund. I returned a dozen or so buckets that were running in the low 13's dKH. It should be 8-9 dKH (2.5-3.0 meq/L).
All the salts I've used have had mfg problems from time to time. I would recommend testing each new batch before adding it to the tank just to be safe and for peace of mind.
I also advise that once you choose a brand stick with it or change over slowly. I've had trouble doing large water changes when changing brands.
I use Instant Ocean or Reef Crystals.
Regards,
Kevin