Is an innovative color device designed to detectand monitoring toxic free ammonia. A sensor changes, reversibly from yellow to green to blue, relation to ammonia concentration. Not needed test kits, chemicals or procedures. The device detects amounts of less than 0.05 mg / L of free ammonia and alerts you of murderer main aquarium before it appears any signs of stress. Ammonia alert lasts more than a year. For use in fresh and salt water. In the absence of free ammonia the unit assumes a faint yellow or greenish yellow. It is normal for the dry sensor to have a greenish tint. Not required water samples, chemicals or procedures. The presence of free ammonia is monitored continuously with a response time of about 15 minutes. The response to the decrease of ammonia is slower, requiring about four hours to go from TOXIC to books in the elimination of ammonia.