you want your heater in the tank not to be constantly turning on and off so keep it adjusted according to the room temperature so that is either on or off for long periods of time.I live in a country where summers are extremely hot and humid. Temperature often hits 40 degree Celsius. If I turn on AC, how would that impact my cichlids? I usually do not keep the temperature below 20 degrees but is it okay for the fish? The tank and the AC are placed on opposite walls, but not face to face so the cool air from the AC do not directly hit the tank. They have fair amount of vertical distance as the tank is located just couple of inches above the floor and the AC, of course, is close to the ceiling. Please advise.