Hello and welcome - This is a great place to get all of the info you need to have a healthy aquarium.
It says in your info that you don't know about the
nitrogen cycle - a first step is to read the beginner's articles. It sounds complicated at first but as you get advice everything goes back to learning about the cycle.
Do you have a liquid
test kit to know what is happening in your tank? The
API kit is recommended on this site and the tests will let you know if the
ammonia is beginning in the tank - most people recommend to do the cycle fishless. That is covered in more of the beginners articles.
Back to your original question:
I do water changes exactly the same way as Gargoyle and the fish seem to love the fresh water. No salt or other additives besides Prime or Aquasafe or other water conditioners that take away the chlorine and heavy metals in the replacement water.