shaddows in glass/water

when i make glass or transperant fluid,
then there is comming a lot of shaddows, because the light wouldn’t pass trough the transperant object

Well this might have a few different causes…

The most likely is probably that you need to check TraShad in the materials tab for the shadow receiving meshes.
Or if you’re working with Yafray, GI doesn’t allow light to pass through transparent objects - yet.