your calcium and alk levels among other things that arent so easily measured will be skewed and low somewhat due to preciptiation . How much depends on how wet it was, how much caked, and how much mixing it worsened and spread the issue
its trash imo and only good for cooking or cycling rock. not suitable for a display loaded with coral. If you do use it, make sure to measure the crucial parameters to make sure a water change wont drop things out of range
This is why a 50 gallon drum of salt would be a really bad idea for me. i can handle screwing up every so often and toasting a half bucket or so of salt and shrug it off...............a drum would really tick me off
I currently have 3 partial buckets of salt in my garage right now that i have doen the same thing with and I wont use them. I do keep them around though as it is good for some things.......just not my diisplays