Described herein is a buffer device for use with photographic processing apparatus which provides a buffer for solution being fed to or collected from the apparatus. The buffer device (18) comprises a flexible plastic concertina-shaped container (30) having a volume appropriate to the apparatus with which it is to be used. The container (30) is preferably constructed to be normally-closed and requires liquid pressure to open it. The container (30) is fixed at its upper end (38) and its lower end (40) is free to move downwardly when liquid enters it. An index member (32) is attached to the lower end (40) and this member (32) cooperates with a position sensor to indicate to an operator whether the container (30) is "not empty", "not full" or "full".