Since I am still online, I will throw in my two cents. Excess nitrate products can be exported by live rock, converting to nitrogen gas, denitrators, or algae scrubbers. Everyone uses live rock as stage one, but as you have noted, with a heavily stocked tank, nitrates can build up. Most water exchange programs keep them under control, but I don't do massive water exchanges. So I went the natural way and grow beds of harvestable algaes. I put my nitrates into the local landfill. It is natural, stable and pretty easy to setup with a bit of room. But I also boost the bacteria in the live rock with bio pellets. Both work together and support each other.