i like instant ocean.....baltimore aquarium and many many other large aquarium places like it use it....so why not go with what places like that are using...its cheap....and it seems to work just fine...it does take a minute to dissolve but who cares u can use that minute to prepare other things
I really think all of the major brands are close to the same quality; just be sure to use a "reef" salt if yiu're going to do a reef tank---more trace elements (I assume).