To reiterate I would suggest you get a copy of Dr. Rohwer's book "Coral Reefs in the Microbial Seas" as it introduces in a very readable manner how DOCs and not the inorganic forms of nitrogen and phosphate affects the microbial populations either promoting beneficial or pathogenic types and pushes a reef ecosystem to become more or less eutrophic (nutrient enriched). As I understand the DiMyCo website their filter is looking at only the inorganic portion of the nitrogen cycle in the most simplistic circle or form that's been touted for freshwater tanks for decades. It totally ignores what's happening with organic forms of nitrogen like amino acids and urea that are being produced and/or added in food and supplements. It also does not take into account that corals, and algae, are actively scavenging ammonia excreted by fish from their gills for food before it can be broken down into nitrates. Additionally as part of the coral holobiont are cyanobacteria fixing nitrogen gas into nitrates the additional anerobic section doesn't make sense to me. A much better diagram of the nitrogen cycle showing the multiple paths of assimilation and dissimilation, excretion and mineralization can be found on pg 255 of Delbeek and Sprung's "The Reef Aquarium" Vol III.
