Ever since turbulent cleanrooms have found their way into pharmaceutical companies, there have been differing opinions and lively discussions as to whether the classic approach of return air extraction close to the floor can be replaced by extraction via the ceiling without negative effects on the quality of the cleanroom. In our presentation, we will look at the two approaches and first consider the advantages and disadvantages in terms of power requirements and investment costs. Finally, we will look at the room situation using a flow visualization in a practical cleanroom. We will pay particular attention to the flow behavior, the distribution of the particle concentration, the formation of dead zones and heat pockets as well as the recovery time at different points. Together we will discuss the findings and draw possible conclusions.