That would be Prime more then likely. It doesnt remove ammonia it detoxifies it. Which in turn makes it easier to be converted into nitrite then nitrate. I have used Prime a lot for different reasons but mainly to protect fish in a established system from a minni cycle. Ro water should not have any ammonia in it to begin with. It wont hurt anything and prime does not mess with the skimmer like pretty much every other declor does. If you have detectable ammonia then by all means use it, other wise its just a waste of money.