Volume created from Phoenix FD has weird box glow

[steve]

I have read a VDB generated by Phoenix FD and it seems to have a glow that bleeds into the volume. Any ideas - it seems connected to the blackbody emission but I cannot get this fine tuned that I don't get some sort of glow.

The channels can be seen in the attribute editor for the volume - and I added a 3D fractal as some displacement. Rendered with an Arnold IBL dome and a directional light.

Any ideas most appreciated

[steve]

No? Cannot figure it out

[steve]

Ok - I think its an output from Pheonix with temp outputs to grid. A test one from elsewhere works.