Cannot get to export Opacity map

[Veleno]

And here's an upload of a version of the tank with the UV animation fixed. I also added in an example of a disc that scales and moves down with the UV animation to act as the top of the fluid.

I'd recommend disabling backface culling on the fluid by checking the "2-sided" option in its material. I'd also disable blend and enable multisampled alpha on the geometry either through Inspector or through the script.