Activated Carbon - What does it do?
If you have been caring for a pond for a season or two, you’ve probably figured out that there is no one magic wand to keeping the ecosystem healthy. A pond with healthy living water needs oxygenation, circulation, plants, sunlight, filtration, fish, and structural integrity.
Tannins and impurities
Activated carbon can be used to remove tannins and impurities from the pond water. It cleans and clarifies quite well. It removes particles like tannins and chemicals that are so fine filter pads can’t catch them. Tannins are the tea color you may see in the pond. It comes from organic material and often from driftwood in the pond.
A UV light in a pressure filter does not clean up tannins, although it is good at getting rid of microbial or suspended algae because as the algae is exposed to the light, it kills the algae.
The way activated carbon works
Activated carbon is essentially carbon that has been treated with oxygen. That treatment opened up tiny spaces between the carbon atoms. Activated carbon is an ultra-fine filter, able to absorb chemicals and extremely fine particles.
It does not, however, treat nitrates. While it absorbs impurities, nitrates still need to be processed. The pond needs beneficial bacteria and aquatic plants to process nitrates in the pond water.
Carbon is excellent for removing tannins or turbidity* and removing chemicals in the water that typical filter pads, biological filtration and even UV lights cannot.
*(turbidity is the measurement of being able to see through water. If you can only see 4 inches into the water, we would say it has a high turbidity.)
How to use activated carbon in your pond
Activated carbon comes in or with a mesh bag. It often comes in a 5 or 9 pound bag. For every 1000 gallons of water in the pond, you will need roughly 5 pounds of activated carbon. Place the mesh bag of carbon where maximum water flow will pass through it. The skimmer is usually the easiest place to use as long as there is enough room. The Biofall also works although it can be more cumbersome to get to.
When placing it in the skimmer, put it below the basket and filter pad. In 2 or 3 months it will need to be replaced.
Activated carbon has proven to be a highly effective filtration tool to maintain water clarity, remove impurities, and promote overall pond health. When used in conjunction with other tools it can be great addition to your tool box.
If the pond water is green, I suggest using a UV filter and making sure that all the pieces required to have healthy, living water are in place. Read more about microbial algae here. If you want to crystal clear water try using activated carbon!