Wow, quite a difference in the plant sizes between the bright and moderate sides of the tank. I have been tempted to try some root tabs with some of the heavy root feeding plants but, like you said, they'll only do as well as the weakest facet allows and, for me, it's lighting. Right now, I believe that my best tank insofar as lighting is concerned is an inexpensive 20 set that came with an incandescent fixture. I replaced the bulbs that were supplied with daylight CFLs. They seem to give me the intensity I was missing. I might replace all my old fixtures with cheap incandescents if this works out. Floating plants do add a whole new dimension to a tank. You're probably right about the barbs preferring the plants. Maybe try the cucumber and blanched lettuce or spinach and see if that keeps them off the plants. I have a rainbow shark that is currently keeping all of the water sprites and water wisterias in his tank mowed down. Best of luck !