I have used IO, Oceanic and currently I have 6 bags of Reef Crystals. They all work equally well in my experience. The only props I would give goto Oceanic for being way easier to dissolve. Its almost a powder like substance. In my experience all 3 have mixed about the same and have worked well when used on a regular wc schedule. When this salt mix runs dry I plan on trying other brands as well. Agian, in my experience, salt is salt.
Peace.