Method of operation of a perfusion system

A method of operation of a perfusion system, the method comprising:

• inducing, via at least one feed flow control device, a first quantity of a feed fluid to flow along a first direction from a bioreactor to a tangential flow filter via a feed flow path;
• controlling the at least one feed flow control device in the feed flow path, by a control unit, for controlling said flow;
• as a result of said flow along said first direction, allowing the tangential flow filter to separate the first quantity of the feed fluid into a permeate fluid and a retentate fluid;
• operating the control unit to control the at least one feed flow control device to inhibit or stop the flow of the first quantity of the feed fluid;
• and
• operating the control unit to control the at least one feed flow control device to direct a) a further flow of a second quantity of the feed fluid from the bioreactor, b) a portion of the permeate fluid, and c) a portion of a fresh nutrient fluid from a source, along a second direction opposite to the first direction via the tangential flow filter to a waste storage unit for a predefined duration to clean the tangential flow filter.