Carbon

Strictly speaking, to remove every single scrap would actually take a long time.

Carbon doesn't actually adsorb all the chemical in the water. An equilibrium exists with some of the chemical attached to the carbon and some free in the water. This is one reason I usually suggest doing a water change before putting the carbon in so that a big chunk of the med is already removed. And using several small batches removes more as you take the bound med out of the tank with a batch of carbon reducing the total med and meaning more would bind to a new batch of carbon than if one batch was left in for several days.

Having said all that, it only takes a day or two to remove it to almost all of it; so low you can think of it as zero. Maybe even just 24 hours.