An electrophotographic copier for selectively printing in one of a number of different colors in which development takes place at a common station around the periphery of a photoconductive drum to which station a distributor system selectively feeds liquid from one of a number of supply containers and from which the liquid is returned to the container from when it came. Our machine flushes the common portion of the liquid circulating system each time a change in color is made. The processing liquid tanks of our machine are provided with an arrangement for inhibiting settling of toner particles in the tanks.