Well first off it's not impossible to have zero but it is also not very realistic . If you plan on keeping corals and anemones etc...... you should try to keep it below 15 IMO, if its fish only they can handle higher levels, but no higher than 30 IMO. What really worked for me is actually 3 things . #1 Was the natural aging of the tank , I found that as my tank aged past say 6 months then it was a little easier to control.#2 Watch how much you feed!! Its better to underfeed than to pollute your tank with to much food! # 3 Adding a refugium can do wonders for Nitrates, Mine was cheap and easy to set up cost me like 30 bucks and it started to take effect in about a week , dropped mine from a constant 20ppm to 10 and it never goes higher than that. Hope this helps ! :yes: p.s I have many corals and Anemones now with no problems at all.