During the last four years a new cushion module has been commercialised for dead-end ultrafiltration in water treatment. However, system and operation mode optimisation is still subject to research and development activities. For dead-end ultrafiltration one of the key issues is the module flushing procedure. So far, analytical methods for the investigation of particular steps during module flushing are rare and optimisation in most cases relies on operating experience. This paper presents the optimisation of the airpulsing step as part of the module flushing procedure with an approach, which combines lab-scale experiments and analysis of full-scale plant operation. For this purpose a novel method for shear stress measurement has been developed and applied. The results have been utilised for the optimisation of a fullscale ultrafiltration unit for wastewater treatment plant effluent upgrade. After changing the module flushing parameters and thus enhancing the flushing efficiency it was possible to increase filtration performance.