HTHD and HLLE may be Carbon Brand Specific

So I noticed a few days that one of my Chromis had a small white blotch on his head, and my Randalls Assessor had light lines down her side. Nothing serious, but I noticed it since i'm always watching the fish. I knew exactly what it was.. The Chromis had early stage HTHD (Hole in the head disease) and the Assessor had HLLE. I knew instantly what caused it.. I had switched from Marineland Premium Activated Carbon to Seachem Matrix Carbon. There was no Marineland at the store so I had to buy the Seachem. It was only in the tank for one or two water changes, but that was enough.. I removed it, and now two days later both fish are back to normal with absolutely zero residual damage. They look like they are back in their prime.



Just something to think about..