Mayaca and R. Wallichii look very similar, but Mayaca tends to have a thicker stem and more densely packed leaves IME... I have never seen Mayaca get red/pink ends, so if the plant remains a solid silvery-green it may well be Mayaca...
The first one looks like creeping jenny(ludwigia?)
the second one does'nt really look like R.wallichi to me. it really looks like dieing anacharis, but i doubt it.
It may just be the pics, but r.wallichi is pretty pink. And the leaves look a little bit too wide to me.