I've finally mastered 4 carpeting plants in my 12Gal

from the left to right: Dwarf Baby Tears, Marsilea Minuta, S.Repens, and Dwarf Hairgrass.

Now part of the achievement isn't that I've been able to grow and make them fill in, it's that I've been able to keep them algae free for many months now. I think being able to balance your tank is a greater achievement than being able to grow plants that need to be cleaned of algae every other day...especially because its so darn hard to balance high-light nano tanks.