The test that Dr Ron did aside for now ( lots of controversy there ... some merited and some not ) ... this salt has been used in laboratory and public aquarium conditions for years ... I am in no way defending it by saying so because I have not tried it but there are as many success stories as there are " bleach " stories too
There seems to be some anecdotal evidence to suggest that it might not be all that friendly to algae ( in many forms ) but it seems to also be beneficial to fry of all kinds ... very curious indeed
Cheers