Like they said if its adding sodium that can be fine or good for many fish however some aquarium inhabitants are sensitive to salts. Catfish or other fish without scales, invertebrates, and plants don't tend to be ok with it but I couldn't tell you how much would have to be in your water to harm any of them. If you keep anything like that I'd personally look into it a bit further.
Like they said if its adding sodium that can be fine or good for many fish however some aquarium inhabitants are sensitive to salts. Catfish or other fish without scales, invertebrates, and plants don't tend to be ok with it but I couldn't tell you how much would have to be in your water to harm any of them. If you keep anything like that I'd personally look into it a bit further.