It may never matter to you. You may not keep tangs.
In 2009, a survey was taken of 100 advanced aquarists who identified twenty-five suspected causes for HLLE in marine fishes. The majority of the survey participants believed that HLLE in marine fishes such as tangs and angelfish is caused by a dietary problem, notably deficiencies in vitamin C or low levels of highly unsaturated fatty acids. General stress caused by captivity also was cited as a major cause of HLLE. Other survey responses included stray electrical current, the use of copper medications, heavy metal toxicity, lack of sunlight, the use of activated carbon or the presence of a variety of chemical pollutants all as possible causes of HLLE. Viral and bacterial infections have also been implicated in causing this syndrome (Varner 1991, Hemdal 1989). In the survey results, 18 treatment methods were reported to have caused remission of HLLE symptoms in fishes. Eighty-four percent of these cases involved moving the fish to a new aquarium as one part of the treatment. This shows that there are conditions in the physical operation of the aquarium itself that can be changed in order to reduce the incidence of HLLE. When the survey results were limited to professional public aquarists, 19% of the respondents found complete reversal of HLLE by discontinuing the use of carbon filtration. In addition, 75% of this sub-group stated that they felt that the use of carbon caused HLLE in at least some cases.
I do not run carbon. I have it here. If I think I have contaminated my system with something I run carbon overnight.
None of my fish have ever had HLLE
Head and Lateral Line Erosion (HLLE) is the name for a type of skin erosion that affects some species of marine fishes in captivity. It is occasionally referred to as Marine Head and Lateral Line Erosion (MHLLE) or Head and Lateral Line Erosion Syndrome (HLLES). It will cause scarring and greatly affect how a fish looks
I would also like to add 1200+IAV means how well this carbon absorbs Iodine. That rating seems to mean it is very good at that.
Not good to me. I dose iodine for my inverts. It may (I do not know this but am speculating) also remove other trace elements you want in the tank.
No carbon for me except in emergencies.