Using a calibrated refractometer. Both clowns In the tank plus snails were all fine (now so is the CBS)what kind of test you used for the salinity? It seems very unusual that an LFS will keep salinity that high, in fact, almost unheard of.
I think something was off with the salinity test, and if so then you acclimated it to a different salinity for no reason, therefor the reason that it got shocked.
Unless you used a Hanna I would say there was an issue with the test device, just my guess.
I actually remember buying from this store on my previous tank few years ago and was the same salinity then. Other stores I buy from are usually between 1.024-1.027


