Activated carbon is a porous form of carbon that can be used to absorb or remove dissolved organics that give water its yellow tint. Removing these materials will help with biological filtration and increase water clarity. In theory, better clarity will aid light transmission through the water column and improve PAR (Photsynthetically Available Radiation, which is all radiation between 400-700 nm wavelength range)

Does Activated Carbon Remove Beneficial Trace Elements?

One of the big arguments against using activated carbon on a continual basis is that it removes beneficial trace elements from the water. I have used carbon continuously on all of my tanks and have not seen any negative side effects on my corals. This is purely an observation and not based on any scientific facts. According to Dr. Timothy A. Hovanec, who is a noted expert in the field, “activated carbon is going to have no effect on the majority of elements found in seawater”.


Another knock against using activated carbon is that it is unhealthy for certain fish and can lead to head and lateral line erosion (HLLE). A study conducted by Jay F. Hemdal concludes that hard pelleted carbon did not cause severe HLLE, while the soft, dusty carbon did. If you do use carbon, Jay recommends rinsing it well with RO water and using an effective skimmer. It is also important not to place it in a carbon reactor with high flow, which can break it up into tiny particles.

Use The Least Amount Necessary

The amount of carbon one should use will vary depending on the tank. The general guideline is to use the least amount necessary. Over time carbon will lose its ability to absorb materials so it will have to be replaced on regular basis. Each tank is different so the frequency of replacement will vary.


So do the benefits outweigh the minuses when using activated carbon? I am a SPS guy and will continue to use carbon on a regular basis since it improves water clarity. HLLE disease is certainly a downside so I do follow the guidelines of use mentioned above to minimize the chances of it occurring.


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For many more details on using activated carbon, please refer to Timothy’s article on Activated Carbon. And if you are looking for additional insights and information, please explore my many other reef tank and SPS related articles as well as my book, A ReefBum’s Guide To Keeping an SPS Reef Tank: A Blueprint For Success. Additionally, you can see all of my reef tank videos online now as well as my Live HD Webcam.


Happy reef keeping!