# article - Does a Reef Tank Need Carbon?



## sig (Dec 13, 2010)

There is no doubt that the biggest selling maintenance product in the aquarium industry is Activated Carbon. This long time filter media started as Bone Charcoal 150 years ago, and it's been keeping aquarium water sparkling clear ever since.

In the aquarium trade, activated carbon is sold in more products than you think. It is the key ingredient in HOB disposable filter cartridges, and is often blended with ion exchange resins, ammonia removers, and other chemical media that makes up hundreds of aquarium products . And of course, it is sold in bulk or pure form for use in canister filters, mesh bags, and media reactors.

Why do we keep using it? Any veteran freshwater or marine aquarist can tell you that it removes odors, removes color, and makes aquarium water as clear as ice. Despite the beauty of your show tank, no one likes to walk into your living room and get a whiff of that "fishy" smell.

There is a lot of confusion about how activated carbon acts in saltwater, especially when it is used in reef aquariums. Here, aquarists are constantly pushing for a more natural filtration approach. But it bugs the hell out of me when I read all the misinformation on the Internet and even on carbon product labels. They preach to use carbon sparingly, like one day or three days a month, or don't use it all. Folks, Activated Carbon is non-toxic. It cannot be overdosed. It will not remove all the salts and trace elements and turn your tank into some incomplete blend of synthetic seawater.

We all need to realize that our reef and fish-only aquariums are NOT miniature slices of the ocean. They may look that way, but bio-chemically they are an ecosystem that is always on the verge of collapse. Activated Carbon's job is to remove metabolic wastes, or more commonly called organics. You can employ the deepest sand bed or the largest calcium reactor or a humongous circulation pump, but none of these things will have any effect on organics.

When it comes to organics, the world's oceans maintain a perfect balance of metabolic waste removal through a series of natural recycling systems. Both the volume of water and the immense surface area provides a home for tens of thousands of species of macro and micro organisms that process these wastes. In the home aquarium, just a small fraction of these organisms can survive. Coupled with an extremely high specimen to water ratio, organics tend to accumulate in closed systems, and can reach concentrations orders of magnitude beyond natural ocean levels. Even with aggressive water changes, these organics can never be diluted enough to mimic the natural levels where our livestock has lived for thousands of years.

Don't confuse organics with ammonia, nitrites, or nitrates. The bacteria responsible for breaking down these nutrients naturally thrive in all aquariums. Most tanks are nutrient rich and provide lots of food for these bacteria to thrive. Organics on the other hand, consists of complex metabolic compounds including phenols, organic acids, proteins, fats, carbohydrates, and hormones. To break these down, we don't (and can't) grow the right bacteria in our aquariums. In fact, detritus on the gravel surface and in the bottom of the sump are organic compounds that have reached such high concentrations that they fall out of solution. These particles remain inert as long as pH, oxygen, and ORP levels stay constant. Any wild swings or disruptions will trigger detritus particles to release these pollutants back into solution, causing an avalanche effect which will fuel a tank crash like there's no tomorrow.

Where Do Organics Come From?

Creation of organics is a natural process of fish and invertebrate metabolism. It has little to do with the amount of food added to the tank. Reef tanks are especially vulnerable to organics, since corals and invertebrates produce a lot more organics than fish. Coral "slime" is nearly 100% pure organics. When you are mounting a coral or moving things around, copious amounts of sliming results. This slime is torn apart by powerheads, oozes through mechanical filters, and finally winds up being dissolved in the aquarium water. By contrast, coral slime in the ocean is quickly washed away perhaps hundreds of meters away from the coral. It is then consumed whole by other invertebrates or fish or quickly broken down by specialized bacteria and used by plankton as food. Everything is recycled in the ocean. In the aquarium, it has to be removed.

Why Organics Are Bad

While only a few of the organic compounds are directly toxic to marine livestock, they can stimulate the growth of heterotrophic bacteria which robs your tank of oxygen. These bacteria also create carbon dioxide. The result is lower pH and low ORP, which creates ideal conditions for nuisance algae to thrive. Organics can quickly tint aquarium water to a yellow color which greatly blocks blue spectrum light penetration (actinic 420nm). High levels of organics can also tax a protein skimmer to the point where nitrates and phosphate removal becomes minimal.

No one knows for sure the total make up of organic compounds in the marine aquarium and what specific effects they have on different organisms. It had been observed that aquariums with high organic levels experience more fish and coral diseases. There is now firm evidence that organics stunt fish growth. The old mystery of how a fish will grow only as large as its container has been solved. It has nothing to do with the volume of water or the size of the tank- organics accumulation is the culprit.

At moderate organic levels, corals and invertebrates tend to close or cease reproduction. Some researchers believe that there is a direct relationship between high levels of organics and dense populations of disease organisms. The reduction of naturally occurring organics ultimately leads to improved water quality and healthier specimens. Activated Carbon is the most effective and easiest method of removing organics from aquariums.

How to Tell if Your Organics Levels are High

The tell tale signs of high organics in marine aquariums include (1) Persistent hair algae problems despite low nutrient levels, (2) Some foaming in the sump or in the corners of the tank, (3) An oily film or cloudy layer on the water surface where even a tank overflow can't seem to get rid of all of it, and (4) small growths of Cyanobacteria spotting on rocks and the gravel.

How Activated Carbon Works

Activated carbon is a unique product that starts out as nut shells, wood, or coal. It is pyrolysed in a 750°C oven which cracks the material and creates millions of micro pores on the surface and though the interior of each grain. The surface area of these pores are immense. One gram of granular activated carbon has 5,300 square feet of surface area. By comparison, a tennis court is 2,800 square feet. It is not only the large surface area of carbon that attracts organics, but there is an electrical charge involved that draws organics to the carbon.

► Carbon removes trace elements- Carbon has a greater affinity for organics than trace metals, but it will remove some trace elements. On the other hand, both protein skimming and natural consumption of trace elements by tank specimens will remove significantly more trace elements than carbon. Aquarists concerned about depleted trace elements should be using a trace mineral additive- whether or not carbon is used. Two excellent products for this are the Sera Strontium Complex and the Seachem Reef Trace products.

► Carbon should be used only a few days a month False. This myth was likely started by activated carbon's ability to remove yellow tinting and odor from the aquarium within the first 48 hours of application (or perhaps manufacturers who want to sell you more carbon). The higher concentrations of organics are colorless and odorless and require more contact time for removal. Another complication of part-time carbon use is storage and reuse. Once the carbon is removed from the aquarium it will continue removing contaminants from the air. Placing the damp carbon in a sealed plastic bag doesn't work either, as the damp carbon becomes exhausted servicing die off in the stagnant aquarium water stuck to the grains.

► Spilled carbon causes harm to the aquarium False. Carbon granules that are accidentally spilled into the aquarium will quickly become saturated with bacteria slime, having the same biological effects as a grain of gravel. It may look ugly, but it is totally harmless.

As we have seen, the use of Activated Carbon is an important part of maintaining a healthy marine or reef aquarium. It is the only filtering media that can remove substantial amounts of metabolic wastes (organics), which accumulate over time and can prevent secondary water quality and health problems in specimens. Because of the phosphate issue in lower quality products, it is better to spend a little more on a quality carbon than use any carbon at all

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http://joejaworski.wordpress.com/2008/05/09/does-a-reef-tank-need-carbon/

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## wildexpressions (May 3, 2010)

pretty good article. I once preached against carbon use but in mixed fish/coral tanks I came to believe charcoal can make a significant difference. 

If you are using activated charcoal and you have corals you need to be testing your iodine. Various types of activated charcoals range from moderately absorbent to very absorbent when it comes to iodine.

Which brings up something else. Only use charcoal specifically designed for aquarium use as their are a significant number of differing types, many of which use noxious additives to alter the pore structure of the finished carbon. The result is they are more or less tuned to specific elements, gases, compounds, etc making them range from moderately good to useless for removing the type of organics we are targeting in the aquarium. Some of them still contain traces of those fairly obnoxious compounds that would be better off not introduced into an aquarium. 

I'd be interested in your opinion of coral only tanks.

I still have not come to a conclusive opinion when it comes to coral tanks. I know that most good aquaculture tanks are very low nutrient environments. So much so that many corals will not color up in them even though they may grow at a good rate. It is a matter of great interest to me. I am in the process of setting up aquaculture tanks and have been reading a significant amount on the issue. 

The direction I am going so far is to only use carbon for a couple of days after adding or harvesting corals from a system. I do not handle my corals at all otherwise. My logic is that I am adding amino and fatty acids and carbs a couple of times a week as well as iodine all of which are readily absorbed by activated carbon....seems counter productive to me.

It is possible that once I get a number of tanks running I will find that I will end up with tanks oriented on specific types of corals grouped together by those that benefit from the use of carbon and those that do not. I believe it is something that I will simply have to experiment with and figure out myself.


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## carmenh (Dec 20, 2009)

Great article. I'm going to start using carbon more often, and will definitely upgrade the brand I buy, since Black Diamond gets the so-so rating...


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## adrenaline (Jan 17, 2011)

excellent article!!! I use carbon in every freshwater tank i have, but I was skeptical with all the myths out there about it in reef tanks. This makes my life easier, I like using carbon. the only problem is i need to buy more carbon oly packages as i've been using the amo-carb mixes from seachem and black diamond in my cichlid tanks. I'm assuming the ammonia removing substances probably arent reef safe, as it does state not for marine use on the packaging. 

But i'm very happy to hear i can use carbon in my marine tank. I've been supplementing with seachem trace elements, and even with regular t5 lighting my corals have been growing and splittingl ike crazy. my 2 musroom frag has become 6 mushrooms in a little over 1 month!


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## solarz (Aug 31, 2010)

sig said:


> Don't confuse organics with ammonia, nitrites, or nitrates. The bacteria responsible for breaking down these nutrients naturally thrive in all aquariums. Most tanks are nutrient rich and provide lots of food for these bacteria to thrive. Organics on the other hand, consists of complex metabolic compounds including phenols, organic acids, proteins, fats, carbohydrates, and hormones. To break these down, we don't (and can't) grow the right bacteria in our aquariums.


This is the biggest problem I've found with this article. I'm not a chemist or biologist, so correct me if I'm wrong, but isn't ammonia the byproduct of organic compounds breaking down, i.e. decomposition? Why does this article claim that organic compounds can't be broken down (and thus requires activated carbon to adsorb it), when that's the entire basis of the nitrogen cycle?


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## wildexpressions (May 3, 2010)

solarz said:


> This is the biggest problem I've found with this article. I'm not a chemist or biologist, so correct me if I'm wrong, but isn't ammonia the byproduct of organic compounds breaking down, i.e. decomposition? Why does this article claim that organic compounds can't be broken down (and thus requires activated carbon to adsorb it), when that's the entire basis of the nitrogen cycle?


you are right of course. Most organic compounds can be broken down in the normal process of filtration and as I pointed out many of the organic compounds targeted by carbon are used by corals.

It certainly is no where as clear as this article attempts to make it seem and people reading it should not just jump to the conclusion that this answers their questions on the subject. If you run around the internet thinking every intelligent sounding person who writes an article clarifies an issue for you you are not long for this hobby


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## sig (Dec 13, 2010)

have no clue about it and here is from Wikipedia

"An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon such as diamond and graphite, are considered inorganic. The distinction between "organic" and "inorganic" carbon compounds, while "useful in organizing the vast subject of chemistry... is somewhat arbitrary".[1]

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## wildexpressions (May 3, 2010)

sig said:


> have no clue about it and here is from Wikipedia
> 
> "An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon such as diamond and graphite, are considered inorganic. The distinction between "organic" and "inorganic" carbon compounds, while "useful in organizing the vast subject of chemistry... is somewhat arbitrary".[1]


The original post defined organics as "metabolic wastes, or more commonly called organics." which is more or less the normal definition in aquarium forums disccusions.

The normal definition has nothing to do with the chemical definition in any but the very broadest of senses. In college I did 2 years of Chem Eng. specializing in Enviro. Even there we typically used the term organics in the broadest sense every where except in organic chem class. I'd suggest keeping the tone of the discussion the same and ignoring the chem definition as it will just confuse people, myself included 

Plus the broad definition is applicable here. Aquarium charcoal is designed to remove relatively large organic compounds such as metabolic and other plant/animals based wastes.


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