If it has a white, cloudy look, then it's a bacterial bloom. While it is a nitrifying bacteria, it's not the same type of bacteria that you're trying to cultivate for your tank's cycling process. This type of bacteria is in direct competition with the bacteria that you want.. So it's not really a "good thing". That said, it's not the end of the world either. It will usually sort itself out, but if sticks around you'll need to take steps to get rid of it.
Adding more carbon to your filter won't have any effect, but physically removing it via water changes will help.
Are you doing a Fish-In or Fishless cycle?