I know this is now REALLY REALLY old to reply to, but I just wanted to make sure this is noted, I contacted countdown last week asking about what (if anything) other than ammonia and water is in homebrand cloudy ammonia and it does contain substances which may be harmful to fish. Their reply was that it also contains "Surfactants and a clouding agent" surfactants being a wider group that contains detergents, so I wouldn't recommend using it for cycling a tank.