Originally posted by spmnarciso
And I don't have a smell, I was just wondering as to why people use it.
Activated Carbons / Charcoals - The Rundown
by Richard M. Greenfield
First published in the (now closed) British Marine Aquarists Association Journal
Aquarticles
Why is activated carbon used in aquaria?
We are all aware that the aquarium livestock generates toxic ammonia, which is converted in steps to relatively harmless nitrate by bacteria living in the filter bed. There are, however, a number of other contaminants generated in small amounts by the life process which can, over a period of time build up to a high enough to affect the health of the inhabitants of the aquarium.
A slight yellow tinge to the water can indicate the presence of at least one such contaminant. The most important function of activated carbon is to remove these impurities before they reach levels high enough to cause distress or organ damage.
Activated carbon performs other important tasks in the aquarium as well, removing toxic dissolved gasses such as hydrogen sulphide and methane, which result from imperfect water circulation. It acts as a catalyst to quickly convert dissolved chlorine gas to relatively harmless hydrogen chloride. It provides crystal clear water by removing minute suspended solids and colloids - those particles too small to be trapped by filter floss. It helps defend aquarium life on some occasions of accidental introduction of toxic substances such as pesticides,paint fumes,cigarette fumes and the like.