Hygger Mist Maker uses high-frequency ultrasonic vibration to tap water into natural and relaxing mist to achieve mysterious fogging in no time! No chemical and dry ice was used. 24 V low voltage DC powered design keeps you and your fish safe. It is ideal for aquarium, fountain, pond, water feature, botanical garden, and any other places you want to create a mysterious look. Fog maker will be off when it comes out of water, and will restart when fully submerges. As the water evaporates quickly, please always keep the mist maker fully submerged, and fill water as needed.