The Auto Top Off (ATO) System for the Ultum Nature Systems Reef System increases water capacity, offering added convenience for aquarium maintenance.The design includes a proprietary soft-close refill drawer, allowing water to be added easily and without spills using the included funnel. This line is specifically designed for compatibility with the UNS Reef System aquarium series and reduces the need for frequent water level monitoring. Key Features and Important Notes Automatic water level regulation: The UNS Reef System ATO ensures water levels are stabilized and reduces the need to manually top off aquarium water caused by natural water evaporation. Reduces salinity fluctuation: Water evaporation can lead to changes in salinity level. Fluctuating salinity levels poses several risks in a marine aquarium and ensuring stability is one of the keys to a healthy and successful marine tank. Time saving. Product Specifications R60 ATO Dimensions: 6.57 x 9.33 x 7.18" | 16.7 x 23.7 x 18.24cm Chamber Capacity: 2G | 7L Build: Acrylic R90 ATO Dimensions: 10.35 x 10 x 13.58" | 26.3 x 25.4 x 34.5cm Chamber Capacity: 6G | 23L Build: Acrylic R120 ATO Dimensions: 8.66 x 11.96 x 15.84" | 22 x 30.4 x 40.24cm Chamber Capacity: 7G | 27L Build: Acrylic R150 ATO Dimensions: 11.02 x 11.33 x 15.84" | 28 x 28.8 x 40.24cm Chamber Capacity: 9G | 32L Build: Acrylic R180 ATO Dimensions: 13.07 x 11.18 x 15.84" | 33.2 x 28.4 x 40.24cm Chamber Capacity: 10G | 38L Build: Acrylic What's Included UNS Reef System ATO Float Valve Refill Funnel