Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Keep some carbon in the cupboard to remove medicines if needed. But I have not kept carbon in the tanks for years.
Not regenerable using methods commonly available at home.
Activated carbon has an afinity for organic molecules, though it will pick up non-organic molecules, too. In terms of plant fertilizer, carbon may remove chelated iron, but probably does not bother the other fertilizers that are normally dosed as salts.