We recommend cleaning your essential oil diffuser frequently, especially when you change your selection of essential oils. Regular cleaning is important to maintain the life of your unit. To avoid buildup, please do not let water or oil inside the unit when not in use. Over time, water, mineral or oil buildup on the vibrating disk can decrease the effectiveness of your ultrasonic diffuser. A good way to remove possible buildup is to mix ¼ cup of white vinegar with warm water. Let it soak inside the water well for 3 hours. Do not turn the unit on while soaking. After 3 hours, dump out the water and use a cotton swab to gently wipe away any loose buildup from the vibrating disk. Do not push hard on the disk. Rinse the unit out and fill with clean cool water.