Maybe she means kosher salt! Dunno, people call stuff differently in different places sometimes. No need to be harsh tho
Aside from the water quality & maybe stocking problems (don't know without the tank size and fish list), there is some debate on using salt as a preventative in water all the time. And then even beyond that, there is more debate about using salt with scaleless fish (loaches, corys).
Joanne, let us know more details so someone can try to help.