i would stop using the purple up. i would also get test kits for all of those before adding them. you can really screw up a tank and kill corals blindly adding.
as far as a calcium additive goes, you can't just add calcium. your alkalinity will be effected as they sort of work with each other. this is why companies sell "2 part" additives, both a calcium and alkalinity supplement.
i have never added strontium or iodine to any of my tanks. if you use a reef grade salt, you shouldn't need to either.