An acceptable range for fish-only tanks is from 10 to 40 ppm.
Although fish-only tanks may run at much higher levels, sometimes with no ill effects, this is not recommended. In reef systems even a minor level of nitrate can cause damage as well as death to delicate corals, anemones and other invertebrates, as well as some crustaceans. The acceptable range of nitrate for reef tanks is 0.25 ppm, but not more than 5 ppm.
However you can achieve 0 nitrates with a denitrator. I cant post links but if you go to google and search "denitrator" and click the Go On, Get Your Nitrates Out. - Salt & Freshwater by "erbio"
send them an email, they might have one in stock...