Your test shows one type of ammonia like
kno4te
said, Prime binds ammonia all kinds and nitrite ...meaning that yes it "sticks" to it making it "safe" for fish and "pulling it" out of suspension in the water, so it shows up on tests where normally it wouldn't. That's part of how Prime works to help make the water safe for the fish. I am not a chemist so I don't know all the fancy terms or all the road maps of how it happens either. But it is supposed to trap the ammonia and nitrite to make it harmless for fish but it still keeps it available to your bb. Not exactly sure as to why that makes it show on tests more readily or in a greater abundance then is actually in the water, it may not even be more then is there it may just screw with one of the chemicals in the test. The Prime tech line didn't give me any real scientific reasoning. That makes me think its the reason people say don't use prime with "xxxx" product it doesn't work while they are actually working just fine together but tests are thrown off by it.