I have found personally when I add my salt slowly to the full amount of water and a pump circulating I get no residue. If I add the salt first and pour the wate rin it flashes and all heck breaks loose. If I dump the salt in the full amount of water its a little better but still get some flashing and residue. Pour it slowly cup by cup and let it dissolve and no issues at all. I have also found Oceanic dissolves much quicker than the IO products and Red Sea I used to use.

Certainly not scientific but my personal experience over the last 35 years.