hi
the problem you have with getting readings from loads of other people, is you cant guarantee that everyone is using the same batch number test kits, the same refractometer/hydrometer, whether they have actually calibrated it correctly, temperature of sample, cleanliness of vials, whether they have mixed the salt well enough etc etc
so.....
if you want to do something like the study i did last year, you are better off getting people to send you salt as i did then conduct each test in teh same manner with the same test kit
have fun!
muzzy