A method of controlling a centrifugal separator, the centrifugal separator comprising a separator rotor delimiting a separation space, a stack of frustoconical separation discs arranged inside the separation space, a drive arrangement configured to rotate the separator rotor about a rotation axis at a rotational speed, an inlet for a liquid mixture, a first outlet for a light liquid phase arranged in fluid communication with a central portion of the separation space, a second outlet for a heavy phase, and at least one tube (26, 26') extending from at least one radially outer portion (28, 28') of the separation space towards a central portion of the separator rotor, wherein the at least one tube (26, 26') has an outer end (30, 30') arranged at the radially outer portion (28, 28') and an inner end (32, 32') arranged towards the central portion of the separation space, wherein the second outlet is arranged in fluid communication with the inner end (32, 32') of the at least one tube (26, 26'), and wherein the method comprises steps of: - rotating the separator rotor at a first rotational speed, - providing a liquid mixture to the inlet, - separating the liquid mixture into at least a light liquid phase and a heavy phase in the separation space, - leading the light liquid phase to the first outlet, - leading the heavy phase through the at least one tube (26, 26') from the outer end (30, 30') to the second outlet, characterized by - changing the rotational speed of the separator rotor from the first rotational speed to a second rotational speed, such that a heavy phase accumulation at a periphery of the separation space is displaced in a circumferential direction. the at least one tube (26, 26') has an outer end (30, 30') arranged at the radially outer portion (28, 28') and an inner end (32, 32') arranged towards the central portion of the separation space, wherein the second outlet is arranged in fluid communication with the inner end (32, 32') of the at least one tube (26, 26'), and wherein the method comprises steps of: - rotating the separator rotor at a first rotational speed, - providing a liquid mixture to the inlet, - separating the liquid mixture into at least a light liquid phase and a heavy phase in the separation space, - leading the light liquid phase to the first outlet, - leading the heavy phase through the at least one tube (26, 26') from the outer end (30, 30') to the second outlet, characterized by - changing the rotational speed of the separator rotor from the first rotational speed to a second rotational speed, such that a heavy phase accumulation at a periphery of the separation space is displaced in a circumferential direction. - rotating the separator rotor at a first rotational speed, - providing a liquid mixture to the inlet, - separating the liquid mixture into at least a light liquid phase and a heavy phase in the separation space, - leading the light liquid phase to the first outlet, - leading the heavy phase through the at least one tube (26, 26') from the outer end (30, 30') to the second outlet, characterized by - changing the rotational speed of the separator rotor from the first rotational speed to a second rotational speed, such that a heavy phase accumulation at a periphery of the separation space is displaced in a circumferential direction.