G'day Ebbie,
I suspect that, in discussions of salt or fresh water density, the floatability of ice is a distraction. When a given quantity of water (fresh or salt) cools, it increases its density as it does so until it freezes. When it freezes it actually expands and, by definition, becomes less dense than the liquid phase. This means it floats, whether the water is fresh or salt.

On top of that, one of the things we noticed in the Antarctic was that, when sea (and thus salt) water freezes, the ice 'crystals' force the salt out of the matrix, exstruding it and forcing the salt to crystallise. This left a layer of extruded salt crystals on the surface of the sea ice; they didn't stay around long as they always blew away out to sea and the extreme dryness of the wind caused the surface of the ice to ablate (change phase from solid to gas without going through the usual liquid phase in between) and form distinctive scoops in its surface.

Pan ice is lovely, and requires very still conditions (in both wind and water) to form and it rarely lasts long.

More geography.

Cheers, Rowan