Live and learn. I just started to use carbon in my aquarium filter and also kept up adding Seachem Iron. Despite the carbon being in the aquarium a good three weeks already? I one day looked at the nylon sock the carbon was in and it was all a RUST color- So,no doubt Seachem iron is concentrated and no doubt that carbon can still be removing what you are putting faster than you can add even weeks old carbon.
So now,I expect to get even longer use out the carbon..as used between dosings.
So now,I expect to get even longer use out the carbon..as used between dosings.