How about this....
Feature Article: The Development of a Method for the Quantitative Evaluation of Protein Skimmer Performance | Advanced Aquarist's Online Magazine
"Four skimmers having four different reaction chamber volumes and representing four distinct types of bubble generation (needlewheel, venturi, airstone, and downdraft) were tested under the manufacturers' specified conditions. These tests revealed that there was no demonstrable difference between the Euroreef CS80 needlewheel skimmer, the Precision Marine ES100 venturi skimmer, the Precision Marine AP624 airstone skimmer, and the ETSS evolution 500 downdraft skimmer with respect to the rate constant for either TOC or BSA removal. Thus it is fair to conclude that, at least for the skimmers tested under the specified conditions, the individual manufacturers' claims of superior performance are without merit. Whether this conclusion can be extended to other skimmers remains to be seen."
"one of the more interesting observations to emerge from these studies is the fact that all four skimmers tested removed only 20 - 30% of the total organics present in authentic reef tank water."
Feature Article: Elemental Analysis of Skimmate: What Does a Protein Skimmer Actually Remove from Aquarium Water? | Advanced Aquarist's Online Magazine
"One of the surprising observations to emerge from the original skimmer performance studies is that only approximately 20 - 35% of the measurable TOC in aquarium water is removed by skimming. That observation might now seem a little less surprising when viewed in the context of the skimmate component analysis. Thus, only ~ 29 % (25% from the solid + 4% from the liquid) of the skimmate removed by the H&S 200 skimmer from authentic reef tank water over the course of a week can be assigned to organic material. So, skimming does not remove all that much of the TOC present in aquarium water, and the skimmate does not contain all that much TOC."
"The chemical/elemental composition of skimmate generated by an H&S 200-1260 skimmer on a 175-gallon reef tank over the course of several days or a week had some surprises. Only a minor amount of the skimmate (solid + liquid) could be attributed to organic carbon (TOC); about 29%, and most of that material was not water soluble, i.e., was not dissolved organic carbon. The majority of the recovered skimmate solid, apart from the commons ions of seawater, was CaCO3, MgCO3, and SiO2 - inorganic compounds! The origin of these species is not known with certainity, but a good case can be made that the SiO2 stems from the shells of diatoms. The CaCO3 might be derived from other planktonic microbes bearing calcium carbonate shells, or might come from calcium reactor effluent. To the extent that the solid skimmate consists of microflora, then some proportion of the insoluble organic material removed by skimming would then simply be the organic components (the "guts") of these microflora. These microflora do concentrate P, N, and C nutrients from the water column, and so their removal via skimming does constitute a means of nutrient export."
I've yet to see activated carbon or other filter pads cause decline in the systems fauna. As a matter of fact, I have found large populations of cryptic fauna thriving within canister filters because of the available "food stuffs." DOC's aren't necessarily a bad thing and just a measurement of DOM, which can be utilized as a food source for corals. At the same time and as usual, if you cannot find a balance the negative impacts may implicate the system. Fun huh? 
