Stupid question but....
 

Could you have a gravel bed made out of activated carbon? I heard after carbon is dont working the micropores are gread for holding beneficial bacteria.

ummm maybe? it might be toxic to fish like corydoras and plecos if they eat it. an admin will come by and probably prove me wrong but thats what im thinking.

k, is it really carbon or is it coal or is it charcoal?

I wouldn't try it, there's a theory that carbon dust may be what causes hole in the head disease.

AH hole in the head disease sounds horrible!

oscars get it. the name basically names what happens.
:( the oscars usually die but you can treat them when they have hole in the head... :(

whats funny is that hole in the head disease is actually a disease iside the body, not the head.

The kind of carbon we use is not good for a substrate. Once it has removed all the stuff it removes, it begins to break down and if usaed as substarte it will start to release the things that it removed. It is also very abrasive and will really make a mess with water changes. Not recommended from what I have read and heard.

hole in the head can also be caused by general lack of necessary trace elements. bettas are prone to that disease.