I used IO because it’s the cheapest salt and have been proven and consists. It’s also widely available.
I don’t use salt as a way to keep or change the water parameters. The 10-15% waterchange does little to the parameters. Your corals should be the intaking the minerals a lot faster than your water change can provide. In other words, don’t use waterchange to keep up the main parameters like alk, Ca, and mg. Let the ca reactor do the work. It’s much more efficient at it. Use the water change to change out the “dirty” water.
I don’t know if that makes sense or I’m contradicting myself. But I’ve good luck with IO salt, weekly water change, and let the ca reactor do the work.