I'm going to guess the lights are about 6" above the aquarium, my office aquarium is a 20 gallon and the lights are about 8 inches and I have stems and flowers above the aquarium.
Here's the full aquarium shot and you can see the distance between the water surface and the lights, just my guess, if it gets too close it will shrivel up also 120 gallon jan 2015 by RW-Photography, on Flickr
the funny thing is, in my aquarium i have a brownish carpeting plant called hygrophila araguaia, that if I replaced my glosso, would make this tank even more red
more photos coming up soon, my ludwigia pink ovalis is growing well but super slow and my ludwigia var. inclinada cuba has adapted to my aquarium and is growing well.
On the other hand, my blyxa japonica doesn't do well in this aquarium, I've always had success with this plant in other aquariums, so it might be too much light, in a lower lit tank of mine, it's growing quite well