id be cautious using the ammonia with surfactants in it - they can be toxic to aquatic life in sufficient concentrations, and even lower conc's won't do them any good i wouldnt have thought... surfactants are present in a lot of soaps, detergents, paints and other solvents and are an environmental hazard when they enter watercourses in wastewater.
the only place i managed to find pure ammonia was a local hardware store, sold as a cleaning solution