If you look on the right side of the picture I linked above, there's baby tears. No water roots from them, but they weren't in the current of the spraybar.
Last night I did the obvious thing and turned the spraybar around so it's hitting the back wall. There is enough turbulence along the back wall to keep oxygen at a safe level during the night, but the rest of the surface is very calm. CO2 levels seem much more stable and there is no current blowing the ludwigia around.