Matt, the Amazon River, even at its clearest, is not that clear. It is rather murky, to say the least. Any of the plants listed, swords, apondogen, and crypts, will flourish under low light conditions. I currently have a couple of Amazon blackwater tanks with swords, crypt and the like, seems to be doing quite well. I am using T5 full spectrum plant lights. Many times, it's the not the quantity of light (measured in lumens not watts) as much as it is the quality of the light (the amount of spectral light, the amount of the spectrum the light covers).