If your diffuser is not producing enough mist or none at all, it could be because you are using water that is too cold. To correct this, only use lukewarm water in ultrasonic units as they would not work with cold water. Make sure the water level is correct and that the unit is well-ventilated with no excess water in the reservoir. Check your diffuser manual for guidance on troubleshooting. If all else fails, consider the mineral content of your water as it could clog the unit over time.