I used to use IO but as so many people have stated I had horrid algae problems among other issues with my tank, since switching to TM things are peachy again. As someone else pointed out and people just glossed over, this is hardly all the information. You absolutely have to remember that there is other minerals in the salt that you are adding to your water, and that should influence your decision as well, which I suspect is why people have a track record of algae problems with OI, I remeber reading a link once that had some brand of salt that used small doses of copper in their salt mix, just things to keep in mind.