The Nesaea sp"red" is one awsome plant. A great red, not quite as brash as the Alternanthera reinecki. I tried it a while back, and while it grew very nicely, it seemed that it did best in the upper half of the tank. It did not like shading the lower leaves, so spacing betwen stems was a must. It also was prone to nutrient migration, a good indicator plant.
Here is is not long after planting (I had bought it at Aqua Forest in SF):
A couple months later, it had hit the surface a couple times and needed replanting each time. Not one that liked just being "topped", ultimately it was a weed which is why I removed it. The reds held best in the top half of the tank, and any lapse in dosing and it would start moving nutrients fromt the older leaves (as you can see in this shot). Also, see how long the leaves had gotten in my tank, I suspect the initial shorter leaves are either emersed or surface growth. The submersed leaves had a typical Nesaea shape.
I look forward to seeing this one go crazy in your tank.