Clove oil kills moss really good.
So does direct Excel, bleach , H2O2, etc.
Burning wood is how you make a saw cut look lke it's a natural aged weathered look, you burn, then power wash or wire brush it. You can get a wire brush wheel and attach it to a drill, then brush off any rot/burn leftovers.
The carbon is not an issue but is messy in the tank/on your hands when you move it etc, prune etc.