I agree with the Prime issue and API sensitivity. I had a constant and consistent, low level ammonia reading in my large freshwater tank even after water changes up to 70%; the ammonia reading never changed. The fish, however, were full of themselves and extremely active.
When I contacted API, they confessed/admitted that both Prime and AMQUEL could cause a false ammonia reading with the API kits. Of course, I would buy either one on a consistent basis.
I have an RO
unit that I use now due to setting up a reef tank as well but, prior to that, I did two 70% water changes in the fresh using stress coat instead (which I don't like as much as it clouds the water for a day or so) and the false readings went away.
As far as I can see, I haven't had an issue with the reef tanks during the liverock curing process using API and stress coat (prior to using the RO