under certain conditions the surface of the aqua water block is not being rendered, even tho it should be visible.

This is a Forge Bug but there's a PR outstanding! (MinecraftForge/MinecraftForge/pull/4763)

I will make more checks be performed, this is a cause that I felt for the timeframe was fine. Its not a bug but rather something I purposefully disabled though may change it to reenable in some cases. Without the code that causes this you get the issues.

I will look into using the tessellator to render only one side of the face rather than both when blocks are above to achieve the same effect.

seems like the PR has been merged, however we'll need to see if that solved our problem.

@UpcraftLP remove the no rendering code for the water rendering when pointing up that I added

@sekwah41 tried that but it doesn't work quite well. it's not on top of our priority list but if you want you can try fix it.