Smart Level is the new versatile fully electronic water level controller designed by Hydor. Smart Level safely and easily handles the aquarium and sump water level due to evaporation. Designed to be used in the many different conditions that exist in the marine and freshwater aquarium environment. Smart Level technology reduces the problems related to lime scale deposits, bacterial film, and wave action, which ensures the continuous, safe, and regular functioning of the Smart Level control. Info: https://www.marinedepot.com/Hydor_Smart_Level_Control_ATO_System_Electric_Powered_Dosing_Pumps_Top_Off_Plug_In_Units-Hydor_USA-HD01043-FIDPETPU-vi.html