I put rice in my salt buckets in mesh bags. My containers seal very very well, but I won't use salt that clumps that way, so I'm extra careful. And Mr. Florida is correct. Even though salt is meant to to mixed eventually in water, it's suppose to be stored in a dry place. Humidity will ruin your salt.
The settling out of particles can happen with well stored salt too, though. All the granules in the bucket aren't salt, it's a multiple of additives that we throw in, to give it the correct composition. These additives weight different, are shaped different and are sized different from each other. You could be grabbing a different composition of the mixture everytime you scoop.... sometimes you get more carbonate... other times you get more magnesium. If you made the whole bucket one scoop at a time in separate little 5 gallon buckets, the reading would not be the same in each bucket.
Humidity adds to the problems even more because like substances clump to each other and that big ball you have in there could primarily be a single component that now won't be mixed in the proper ratio.
