IME... if you plan to just keep zoas and LPS, you don't strip the water down to 0ppm no3.No. You definitely want some nitrate to go with your phos.
You need no3 at around 5-10ppm. I wouldnt start worrying about no3 until it went above 25ppm
You also want po4 around 0.1-0.5ppm. I'm not concerned until it gets to 2ppm
You aim for those #s.... you'll see a big turnaround