Well, I don't know about any of those people, I didn't know anyone's opinion, I just found out on my own that removing the carbon allowed my fish to heal very quickly. My own theory is more about the quality of the carbon, I think that in the process of producing the activated carbon there are some unwanted by products/contaminants. Some brands may do a good job of washing it out and purifying the carbon from sulfates and other stuff. Anyway, this was personal experience, and AFTER this experience I did a LOT of searchingon the net and I found a big fish farm who did I think some scientific research also, they said they had also found activated carbon to sometimes "trigger" hole in the head...my best advice to people is to make sure they have GOOD water quality FREE of any pollutants, sulfates, nitrites/nitrates, etc...
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Joe
www.cichlidfish.com