yeah i did notice some erosion on my yellow tang, very minimal but still there and ive been feeding him a ton of algae, and has gotten a tiny bit better. ive always been a big fan of carbon but im wondering if it has its place in a tank that houses surgeon fish. so im going carbon less for a while and see how it does. bug recommended it a while back i guess i should have tried it then. even though no erosion was present at the time but i had also been running miracle mud in my refugium which could have been sorta canceling out the carbon since miracle mud claims to reverse and prevent head and lateral line erosion. its funny how there are so many things out there that claim to do this and claim to do that and all your doing is adding something else to remove the effects of another product your using. its actually pretty much just like doctors prescribing tons of medication to patients that they don't need.