Hi,
I saw this picture in I think another post. I read the HLLE disease article which was linked. They say that Carbon has been linked to HLLE. If you are using a profuse amount 24x7, you might want to consider going small amounts part time. Also, low light levels i.e. no lights on during summer to cool down water......may cause stress. I had two tangs get HLLE and both of these conditions were present. I am now carbon free.
Paul