I have created some basic water using the fluid sim. Rendering it with Yafaray with my settings in the file gives me these grey spots in the water instead of shadows. I need it to look more like real water. For example the tutorial (cant make links): en.wikibooks.org Blender 3D: Noob to Pro
I actually got this working after a while. If you are having trouble with dark or black glass/liquids, I found these yafaray settings to be very helpful:
Enable Fake Shadows on the glass material
Enable Transparent Shadows
Set AA Threshold to .02
Set AA Samples higher (8-16)
Place Spot light closely pointing at the obstacle