Help with Protein skimmer.

HI, I have a 55g FOWLR and the tank has been running fine for a long time and the skimmer was just fine but i decided to add carbon just to clean out any impurities. After I placed the carbon in my skimmer started foaming and over flowing. I read that certain things can change the chemicals in the water and cause this so I'm wondering how can I reverse this. I took the carbon out and its been a few days but still over flows.