Quick question: My Limnophila aromatica(and my rotala indica, to a lesser extent) has a nice, deep purple color on its leaves that are closest to the light. The older leaves, however, are a mixture of purple and an ugly yellow(no, they aren't dead). Could this be a sign of nitrogen deficiency? I don't have any pics available where I'm at now, but you can check out my biotope journal and maybe see the limnophila there