Method of operating a submersible agitator, comprising the following steps; 1) providing a submersible agitator for accelerating a suspension, comprising at least one actuator module, at least one fluid accelerator module, a transmission module which transmits the generated kinetic energy to the fluid accelerator module along the same or different axes and gearbox modules which allow adjusting the rotation speed gradually, wherein - at least one of the actuator module, the transmission module and the fluid accelerator module is independent from the others, - the actuator module, the gearbox modules, the transmission module and the fluid accelerator module comprise an actuator module connection surface, gearbox module connection surfaces, a transmission module connection surface and a fluid accelerator connection surface respectively, which match at least one of the respective connection surfaces, in order to allow connection between at least any two of the actuator module, the gearbox modules, the transmission module and the fluid accelerator module; 2) selecting an operation without the gearbox module, with one gearbox module or gearbox modules connected in series, depending on the requirements in order to meet the user requirements for different media; 3) operating the submersible agitator according to the selection without the gearbox module, with one gearbox module or gearbox modules connected in series, allowing establishing different propeller rotation rates depending on the number of gearboxes. 1) providing a submersible agitator for accelerating a suspension, comprising at least one actuator module, at least one fluid accelerator module, a transmission module which transmits the generated kinetic energy to the fluid accelerator module along the same or different axes and gearbox modules which allow adjusting the rotation speed gradually, wherein - at least one of the actuator module, the transmission module and the fluid accelerator module is independent from the others, - the actuator module, the gearbox modules, the transmission module and the fluid accelerator module comprise an actuator module connection surface, gearbox module connection surfaces, a transmission module connection surface and a fluid accelerator connection surface respectively, which match at least one of the respective connection surfaces, in order to allow connection between at least any two of the actuator module, the gearbox modules, the transmission module and the fluid accelerator module; - at least one of the actuator module, the transmission module and the fluid accelerator module is independent from the others, - the actuator module, the gearbox modules, the transmission module and the fluid accelerator module comprise an actuator module connection surface, gearbox module connection surfaces, a transmission module connection surface and a fluid accelerator connection surface respectively, which match at least one of the respective connection surfaces, in order to allow connection between at least any two of the actuator module, the gearbox modules, the transmission module and the fluid accelerator module; 2) selecting an operation without the gearbox module, with one gearbox module or gearbox modules connected in series, depending on the requirements in order to meet the user requirements for different media; 3) operating the submersible agitator according to the selection without the gearbox module, with one gearbox module or gearbox modules connected in series, allowing establishing different propeller rotation rates depending on the number of gearboxes.