This is like an everlasting question where you will find disagreement between different schools of thought, probably with success throughout the entre range from 1ppm to 20ppm. My nitrates were always zero and I was not happy, they climbed to 2 ppm, and because i feed a lot with many anemones they are now at 10 ppm. But for now I am not having any knee-jerk reactions and just watching things carefully. I already have good nutrient export (skimmer, algae scrubber and about 10-15% water chance monthly. So not doing anything else or scrambling at the moment.