So after a fair sized water change on our aquarium this evening, I was a little miffed that the ammonia level had seemingly risen since the pre-water change test.
Not actually believing such high levels could be in our tap water (we use Prime in the tank so the levels are just visible), I did a test just on our tap water and unfortunately the level is close to 1.0ppm. Which explains the increase in the ammonia reading after the water change. Now I did some research and am now aware that it has something to do with the way the water is treated by the city and that it is actually ammonium not ammonia.. info on this topic
I added a bit more Prime than I normally would (before I knew about the tap water) to combat any ill affect the water change and additional ammonia would have.
I do believe that when the tank has properly cycled this will no longer be an issue, and during water changes the use of Prime will help combat any initial harm the ammonium or ammonia will do to the goldfish.