That is a very good salt. If you have problem, it is not because of the salt mix. I don't think he is infected so treatment is likely not needed.
Good water and stability of temp and salinity are what he needed. If you add Kalk, add it very slow (drops at a time in high flow area) or the pH spike stress the animals. The same goes with the Carbonate portion of the two parts additive (can drip faster than drops but not dump in cups at a time).
If you can use automatic top-off, it is best. However if you have to do manual top off, do it at least daily. It seem obvious to me, and most advance reefers, but there are novice out there just top off once a week, or dump in Kalk or CaCO3 direct into the tank. Make sure your temp varied at the most 1-2 degree though out the day. Pick your temp 76-83 are all OK but it have to be stable.
IMO, we run into more problem with too much micro-nutrients than too little. I would not add anything into the tank unless you know what you add and can reliably measure the result.
Also, there are no quick fix in reefkeeping. There are very few magic bullet that take care of a problem quickly. Problem with cyano and things like that need to be taken care of with good tank management. Quick chemical are not the way to go because it does not work and add to problems. The antibiotic you used to treat your cyano will wreck havoc on your biological filtration system which all reef depends on for stability.