Hi
So we can help can you post back with the following please:
Tank size (litres, gallons or dimensions)
Type of filtration
How often you normally change water and how much each time
Test results (test now) for ammonia, nitrite, nitrate and pH
What are the "salts" you are adding? Goldfish are freshwater fish and though years ago people added salt as a tonic this was before the chemistry involved was understood and it's now known that regular addition of salt is detrimental to their health.
Also how long do you have any tank lights on for each day and is the tank next to or facing a window?