it doesnt matter how you word it.
Yep. As long as we all understand each other. Which I think we surely do because this is such a simple phenomenon that we've all done with a rubber duck in the bath when we were a kid.
when its time to turn the cards its density that wins.
Not on the ISS it doesn't. No gravity = no bouyancy.
in this situation the pressure gradient you speak of is negligible or
No, the pressure gradient is constant and non-negligible. That's where the force comes from in the first place. The downward force on top is less than the upward force at the bottom, so the thing get a net upward force. Without that difference there's no buoyancy. Equally of course without a density difference in the two things, there's no buoyancy either, when you define buoyancy to include the object's own weight. Different colored rhinoseroses.
and to try to continue our discussion if a HHO cell is at the bottom of the 10 ft pipe
and less at -50 kPa guage pressure.
Yep. Can you describe this whole new system?