Welcome! In the future, do not throw away your filter- it contains most of your beneficial bacteria. You want to keep your filter until it is literally falling apart. You have most likely thrown your tank back into a cycle and are probably experiencing a bacterial bloom.
The carbon really isnt necessary in aquariums and is really only useful for removing meds or odors (which a tank shouldnt have anyway). As this is now a new filter, I would dump out the carbon & stuff the filter with some polyfill or replace it altogether with a filter foam insert (sponge). Do you have a means for testing your water such as an API test kit?