so whats the point: the particle fluid will not collide with the static object

FLIP is mostly using volume representation of the static object
to visualize how that looks like on Your static object you can turn on Static Object/Collisions/RBD Solver/Volume/Collision Guide and adjust parameters until you are happy or you can also feed SDF volume as a proxy to use instead and set mode to Volume Sample

this volume is further sampled into FLIP's collision field at a resolution specified by FLIP Object, so to check how your final collision field looks like turn on FLIP Object/Guides/Visualization/Collision and you will see it once colliders are within the bounds of the fluid

Hello Thomas,
yep of course I used the volume approach. I just missed to change the mode to volume ;-)
Thanks a lot.