I am sorry David, I got part of my reply backwards. Prime causes a false negative with salicylate tests. The salicylate tests rely on the reaction of ammonia with hypochlorite or chlorine, and, consequently, any aquarium product capable of removing chlorine (dechlorinators and bisulfite based ammonia condition- ers) can be expected to interfere with color development, even when ammonia is present.
Prime does bind with ammonia to render it harmless to your aquariums inhabitants, however, Prime is stronger than other products and is active for up to 48 hours.
I apologize for any confusion my previous email might have caused, I hope that you better understand now. Please let us know if you need more information.