Abstract: A method for controlling at least a part of a pump station including a number of speed controlled pumps, the method is arranged to minimize the specific energy consumption Espec of at least a part of the pump station and includes a sub method, which in turn includes the steps of: obtaining input data, determining the mutual relative relationships between a first value A1 of a quantity corresponding to a first pump speed V1 and a second value A2 of the quantity corresponding to a second pump speed V2, and between a first specific energy consumption Espec1 and a second specific energy consumption Espec2, and determining a third value A3 of the quantity corresponding to a third pump speed V3.