To improve the efficiency of the pump complex with two pumps connected in series paper presents a block diagram of the system with energy efficient regulator of the speed controlled pump. Based on the approximation of catalog characteristics pump expression to determine its efficiency is proposed. The results of the system research in package applications Matlab/Simulink with a smooth change of parameters of the hydraulic network is given. Experiments have shown that while the change in hydraulic resistance network and the hydrostatic pressure in the system at an arbitrary law regulator fulfills a given maximum value of efficiency. Increasing the efficiency of the system compared to the system without optimal controller is 14%. Results advisable to implement in systems where the pumping of liquids filling large containers or tanks.