i hear changing salt when doing water changes can be very stressful on corals, so it might not be that tropic marin pro is bad. I've heard when you introduce new salt, you have to do it very slowly, and not with a new water change.
Do your normal water changes with your usual salt, but in between do like a gallon in the middle of the week for tropic marin, and then slowly increase that into a full water change.