I'm not one to jump on the bandwagon about salts anymore (been burned far too many times on this) but I have to say this one sounds different.
http://www.aquavitro.com/Products/salinity.html
What really attracts me to this one is the batch testing by lot#. So you can look up your salt's #'s online by entering it's batch# or lot#. Brilliant.
I've been hosed by other brands printing #'s on the side of the bucket but finding out that they may as well be complete fabrications. Maybe you need to roll buckets and so on but IMO you really shouldn't have to. If the mixture isn't homogenous enough at the bucket level how can one be certain it's homogenous within the same batch? By publishing the batch# test results, Seachem is upholding this particular product to a higher standard. I'll probably buy this salt next and see how it goes. Also 225gallons is a nice size too.