I often add it to a new tank to help gill function and stop any paricites that may come with new fish....I know we all use quariteen tanks...yeah right. I know we should but most don't so I like to add the salt to help .
Im not an advocate of using aquarium salt if there is the tank is running perfectly.
I would only add salt for ich outbreaks, fungal and bacterial infections and to help
heal scrapes and to help ease "stressed-out" fish.
enroll in the "if it aint broke dont fix it " school.
Small levels of salt improve gill function, and help with electrolyte utilization. This is why many people use it regularly. It will do a number on any live plants, though.
after changing of water.... replacement of tap water, Anti chlorine need to be added, salt adding mainly to make the water to become hard as good as making the pH more stable.