Okay i havent done fresh in a while. I know that in salt you add some type of macro to reduce phosphates and nitrates. but what if any plants can be added to fw to reduce the nitrates?
Live plants will take care of keeping nitrates low. In fact, in a heavily planted tank you end up having to add nitrates back in since the plants use so much.
Even in a lightly planted tank nitrates should be held under control. Not that its an excuse to ignore water changes though
Water changes are definately the BEST way to control nitrates. I have never had plants in my aquariums take care of the nitrates for me, and I've kept some pretty dense planted tanks in my time... however my nitrates were generally lower than in my unplanted tanks.