Transparent fluid?

Hi, I’m trying to create a realistic water simulation and almost everything seem to look fine.
But when I add refraction to my fluid (1.3333) it suddenly get some transparent spots on it :confused:.
Other than the fluid simulation the scene contain a panorama (some footages I roughly stiched together) that the fluid is supposed to reflect, and a background footage for the fluids refraction. I’m uploading my .blend and a rendered footage of the problem.
Thanks!

Attachments

Fluid.blend (805 KB)


OK, I increased the depth for “maximum allowed number of light inter-refractions” and it solved the problem.
The down side is that the render time dramatically increased as well so is there any other way?

Not really. Ray traced light effects like that take time to calculate.