Just gradually switch to the new salt over a couple months. IO costs me $35/200g, RC $55/200, i also use tropic marine pro $70/200g. Ive tried most salts out there & have seen nice reefs with every brand of salt, so its the reefer & not the salt. Imagine that, its the craftsman & not his tools?
IO is sold everywhere & usually clean, but its low in minerals & you will have to dose / calcium reactor for SPS & LPS reefs.