Activated charcoal and additives

I have a question about using additives when one's filter has activated charcoal. If I add Seachem Excel to my tank, doesn't the charcoal grab it all? Charcoal has a huge capacity to trap bad chemicals, but wouldn't that be true of the good chemicals too?

Does ChemiPure act similiarly to activated charcoal? Is it also grabing the good/bad/ugly chemicals as well?

Thanks in advance.