In the development of the continuous descaling process by pulling the hot rolled strip through acid tanks, the strip velocity was steadily increased by process technology innovations. Tunnel-type pickling tanks are state of the art. Among other types of tanks this particular type allows strip velocities up to 7 metres per second. The main challenges at high strip velocities are to maintain a complete wetting of the strip inside of the tank, a homogeneous supply with fresh and hot acid as well as a high flow turbulence that improves the pickling process in general. In terms of demanding highest surface qualities the contact free bearing of the strip on the sliding stones is essential in order to avoid scratches or surface defects. In this contribution these effects are analysed and proposals for design optimisations and continuative investigations are presented.