Material Flash?

[Doc]

Good Afternoon,

I'm experiencing a strange color variation to a water material in an animation.  The beads are animated to represent flow in a centrifugal pump.  Certain frames show as light blue and certain frames show as dark blue.  Could this be due to reflections or shadows caused by the moving turbine?

Settings:

Material - Water w/viscosity set to 1.47 (oil) and transparency set to 10.

Environment - Shadows, Caustics, Global Illumination, pretty much anything that can reflect or cast reflections/shadows is off or set low.

Any help would be greatly appreciated. Thanks!