Help Fluid rendering - transparency / translucency

[Mitch@PG]

Fluid is transparent by default, but it has some color absorption.

Just set particle color to white (in the ParticleRenderer component) and the material thickness scale to zero (for instance, the ThickFluid material, or any other material that uses the Obi/Fluid/DielectricFluid shader. Make sure you actually use this material in the FluidRenderer component!). This will yield completely colorless, transparent fluid.

Yes ... heh ...     ... about that ...

So, that odd things happen when you put transparent objects inside other transparent objects .... and I didn't realise that the objects I had inside the fluid had their shader set to transparent.  I swapped the shader back to the standard shader, and suddenly they all appeared.  

Thank you for the above information though - it's helpful to have it laid out clearly.