agree with what's been posted, there is NO substitute for water changes.
having said that, there is options BUT.... plants will only reduce them somewhat, chemical pillows IMO are a bad idea all the way around, building or buying a de-nitrator could be fairly expensive and extremely technical (not to mention risky) and the same can be said for allowing it to occur naturally. for de-nitrating to occur there has to be an anaerobic situation, was what i understood from my reading, the by-products of this could wipe out your whole tank in hours. literally kill all of your fish, and even if you knew what was happening, at that point you wouldn't be able to prevent it. anaerobic situations are something even experienced people tend to stay away from.
i would suggest major research on the subject before you contemplate it, as one mistake would empty your tank.
water changes are the best option.