Chemical filtration is just what is just what it says -- it is the use of chemically enhanced products to remove something from your aquarium. Beware of fantastical claims of effectiveness. The aquarium industry is not regulated to enforce accurate advertising claims. Some of the flat out lies are truly disturbing.

Chemical filtration is completely optional, and should only be used until a specific problem is resolved, with the exception of activated carbon which is good to use at regular intervals.