In 2001, when I started reefing, I used IO with a lot of success. Then they changed their recipe and I almost killed my tank.
I've now been using Oceanic for a couple years till I switched from Oceanic to ReefCrystals, because I wanted a salt mix w/ higher alkalinity. I was surprised to see the health, growth & colors of my corals from Stylophora and Pocillopora to Sarcophytons improve within days.
I also started adding Salifert's trace element mix, potassium iodide and chelated iron 4 weeks ago.
I mix sodium carbonate into my topoff water to replace alkalinity and add a tablespoon of dissolved calcium/magnesium/strontium chloride mix every two days.
Cheers,
John