A method and a system and a container system for transferring separation resin from at least one first container (3； 3； 3a, 3b； 3a′；, 3b′；, 3c′；, 3d′；) to a second container (5； 5′；), wherein said first container is a deformable, single-use separation resin storage container, said method comprising the steps of:—；preparing (S1) the at least one first container by providing a deformable, single-use container comprising an outlet port (4′；) with a predefined volume of separation resin in a storage solution；—；fluidizing (S3) the separation resin in the at least one first container to provide a resin slurry, said fluidizing being performed by mechanical interaction to the first container from an outside of the first container to provide a deformation of said first container；—；fluidically connecting (S5) the outlet port (4′；) of the at least one first container to an inlet port (103) of the second container；—；transferring (S7) separation resin from the at least one first container to the second container by generating a pressure difference between an interior of the second container and an interior of the first container where the pressure is lower in the second container.
