What kind of lighting do you have over the tank? My experience is that if you have a "standard" hood, you're not going to have enough light intensity to keep many plants at all. There are a few you might could get away with. (Java fern comes to mind.)
Also, as a general rule of thumb, do research before you buy any plants at the LFS. It is not at all uncommon to see terrestrial plants sold in aquarium shops and they simply can't live underwater.
Finally, I'd argue that plant's don't pollute the water so long as they're alive. In fact they actually absorb some of the fish waste as fertilizer.