Cutting Chemicals and
Contaminants with Aquarium Charcoal
When it comes to aquarium
filtration systems, there is no shortage available to hobbyists looking to keep
their fish’s environment clean and healthy.
Using aquarium charcoal as part of a chemical filtration regime is a
viable option due to its ability to break down dissolved organic compounds
(DOC’s), odor and color contamination in tank water.
What is Aquarium Charcoal?
Aquarium charcoal (also known as "activated” charcoal or carbon
is a substance popularly used in filtration systems as a means to adsorb
chemicals and harmful organic waste in the water. These chemicals could potentially stress or
weaken the fish, while things like phenols lead to unwanted "fishy” odors in
aquariums. Because charcoal is a highly
porous substance, it has the capacity to attract and hold these organic
chemicals inside of it, such as:
- tannins (leading to discoloration)
- phenols (leading to odor)
- chlorine and chloramine (used to sanitize
tap water of bacteria)
- hydrogen sulphide
- detergents and contaminants such as bleach
- small amounts of heavy metals such as
mercury, iron or chelated copper, and
successfully adsorbs medications, it’s important to note that it should be
removed from the filter before treating fish for any sickness or disease. Once the treatment is completed, the charcoal
can be safely reintroduced to the tank.
Forms of Aquarium Charcoal
Often coming in the form of a black sponge or small granules, coal or
wood-based charcoals are commonly used in most filtration systems. The typical form used in aquariums is GAC, or
granular activated carbon. When deliberating brands of charcoal, it’s
important to consider weight for the given volume. Lighter charcoal (though more expensive)
tends to yield better results due to its increased porousness and ability to
adsorb unwanted chemicals. Fine
particles in the water can clog the tiny pores of the charcoal, but most
filters use a fiber pad in the water flow to prevent this from happening. Additionally, DIY methods, like an old
stocking, can serve as a handy solution to keep your filter free from
Because charcoal binds with
the organic compounds it filters from the water, it eventually becomes
saturated and loses its capacity to remove these contaminants. In order to remain effective, it must be
regularly changed, with the typical rule-of-thumb being every 2-4 weeks. However, occasionally rinsing the charcoal
can temporarily refresh the batch to extend its lifespan and use.
What it Doesn’t Do
Charcoal will not eliminate ammonia from the water, but instead leave ammonia
traces behind in the process of chlorine removal. This ammonia is highly toxic to fish and
enters the aquarium water through a number of ways such as the tap or through
the decomposition and breakdown of proteins.
Additionally, aquarium charcoal will not remove nitrites or nitrates,
which means that other methods such as water changes must be used when
initially setting up your tank.
Proper maintenance of an aquarium is essential to the preservation and
longevity of your fish while keeping them healthy and stress-free. Using aquarium charcoal in a water filter
helps keep their environment clean by absorbing harmful organic waste, while
also eliminating unsightly colors and undesirable odors from the tank.