Not All Carbons are Made Equal

[ILuvMyGoldBarb]

I've been considering the value of activated carbon lately in a reef aquarium, and I cannot deny it's profound impact and it's ability to greatly increase the quality of the water. Like most people, I always thought that activated carbon was a form of chemical filtration; that is in fact not the case. Activated carbon is a form of physical filtration. Here is an excerpt from Seachem's website concerning activated carbon.

While carbon is generally considered to be a chemical filter, that is not precisely true. It is in fact a mechanical filter as well, but it is only capable of mechanically filtering objects of molecular size. It functions through extremely small cracks and crevices, called macropores and micropores. Microporous carbons remove primarily metals and smaller ions (like trace minerals) and are best suited to air filtration, while macroporous carbons remove primarily larger organic molecules (like nitrogenous waste) and are best suited to water filtration.

So, while all carbons filter as described above, not all carbons will do that job with equal quality. I'd heard from one of the leading hobbyists in this country that traditional chopped up carbon grains were not really appropriate for reef tanks, but I was skeptical, that is, right up until my test. About 8 months ago, my Toadstool closed up for almost 10 straight days and would not open, when it did finally open, it was only partially. At that time I was advised to remove my carbon as it was a traditional grain carbon. Within 2 days, my Toadstool was fully opened and back to it's previous glory. Recently, I decided to again try this carbon in my tank. Within 3 days of adding the carbon, my Toadstool closed up and went back to that same look. Not wanting to mistake it for a normal sloughing period, I waited for 5 days and then removed the bag of carbon. Just one day later, the Toadstool opened up back to it's normal size again.

Traditionally, the carbon we use in our aquariums is simply chopped up and every grain is a different size and a different shape. The problem with this, is that the allows the carbon to pack together rather densely when placed in water, furthermore, it allows for a more leaching of materials back into the water. Spherical beaded carbon does not compact and allows for much better water flow through and around the particles, thus trapping more organic molecules. For a reef tank, the ability to trap the organic molecules, while allowing the trace mineral ions to pass through is a huge plus. Those trace minerals are vital to the health of corals and such. The use of a spherical beaded carbon will allow the reef keeper to reduce the frequency of trace element dosing. At present, the only spherical beaded carbon that is available on the market is Seachem Matrix. The value of this kind of carbon has been recognized by a number of the leading reef hobbyists in the US and around the world.

This is one reef keeper that is thoroughly convinced of the value of a spherical carbon and I will be switching to it for my reef.

[Fishguy2727]

It needs to be specified that Seachem Matrix and Seachem Matrix Carbon are not the same. Matrix is a biological media that allow for denitrification, the Matrix Carbon is the spherical carbon mentioned above.

There are other pelleted carbons available. Seachem is one of the best companies in the hobby in my experience, but for those who want to use carbon there are other options. I have always considered the pelleted carbons to be the highest quality.

I consider Brightwell Aquatics to be the best company out there for reef products and they also offer a pelleted carbon. (just so people know their options)

How often do you use carbon?
For how long?

[kaybee]

Strongly agree with the title of this thread.

ILMGB, what's the correlation between your carbon usage and toadstool polyp retraction? It seems like carbon usage adversely affected your coral.

fyi, I use small-particled lignite carbon (grain diameter 0.5mm-1mm, grain length 1mm-2mm).

[ILuvMyGoldBarb]

There are other pelleted carbons available. Seachem is one of the best companies in the hobby in my experience, but for those who want to use carbon there are other options. I have always considered the pelleted carbons to be the highest quality. [quote]

That is true, but they are the only one that sells a spherical pelletized carbon fishguy, and that was why I was very specific about that.

[quote]How often do you use carbon? For how long?I run carbon 24/7 on my reef, or rather, once I get the MatrixCarbon I will be doing so again.

Kaybee, the kind of carbon I used did have a profound effect on the coral. It was the only change made to the system each time the coral closed up, and once the change was removed it opened back up. This is an issue that has been reported by other reef keepers as well. Keiron Dodds was the first one to bring it to my attention that the carbon was the issue, it was then that he told me about the difference between carbons.

[Fishguy2727]

Wouldn't a pellet do the same thing, prevent compaction and allow flow through the media better, not just around it?

[ILuvMyGoldBarb]

It probably would, but not as consistently as a spherical pellet.

[Wild Turkey]

Even though im not that into sw i still find this a great read! Some interesting aspects of charcoal i hadnt thought about.
I dont know about anyone else but for this raises more questions...esp. since i usually dont use charcoal and never on the long-term...
Whats the effect on fw tanks?
Does this mean traditional carbon filters will eventually reduce the buffer in the water? (removing trace minerals?) How about minerals my plants would use?

The physical not chemical aspect is easy to understand...essentially it takes crap out of the water, just on a molecular level...cloudy to clear. Guess i just never thought about it before.

[lovleeko]

Even though im not that into sw i still find this a great read! Some interesting aspects of charcoal i hadnt thought about.
I dont know about anyone else but for this raises more questions...esp. since i usually dont use charcoal and never on the long-term...
Whats the effect on fw tanks?
Does this mean traditional carbon filters will eventually reduce the buffer in the water? (removing trace minerals?) How about minerals my plants would use?

The physical not chemical aspect is easy to understand...essentially it takes crap out of the water, just on a molecular level...cloudy to clear. Guess i just never thought about it before.


I have also been doing a lot of reading about carbon. I like you WT have no clue about SW but I do keep reading that carbon and plants can be a problem. I think I'm about to use a bit of carbon because one of my fish tanks has a fishy smell. Which normally doesn't happen. I dont know what's up there. So I might try some carbon and see how that works out.

[ILuvMyGoldBarb]

The wrong kind of carbon and plants can be a problem. First of all, the nitrogenous material is essential for plant health. The major concern comes in the removal of the smaller particles like Iron, Potassium, and other essential minerals for plants. However, most aquarium carbons are made from a macroporous form of carbon and removal of those essential elements does not happen at as high a rate as it does with microporous. The use of carbon will remove some of those those elements, however they are all usually replaced regularly by hobbyists anyway. In a SW environment, the value of the removal of the nitrogenous waste far outweighs the small amount of trace elements being removed.
As for removing buffering capacity, that isn't really going to happen either because of the makeup of the carbon. The carbon used in aquariums is generally a macroporous material and thus it does not remove the Calcium Carbonate ions enough to create a problem.

[Wild Turkey]

Thanks for the info bud! :thumb:

[Fishguy2727]

What nitrogenous wastes does carbon remove? I have never heard of it removing ammonia, nitrite, or nitrate in any significant amount.

Many aquarists have seen an improvement after stopping the use of carbon in their planted and reef tanks.

I don't see how any micro or macropores can remove much of anything since water takes the path of least resistance. So between going through a pellet and around it the water will go around it.

I think the pelleted/stick shaped carbon would be just as effective as spherical, but I am sure Seachem doesn't want anyone to think so.

[kaybee]

...Many aquarists have seen an improvement after stopping the use of carbon in their planted and reef tanks....

The diversity of reef tanks is so great that the opposite can be said as well (many aquarists have seen improvements after using carbon).

Carbon is very effective against neutralizing the effects of coral allelopathy (not an issue if one doesn't keep corals which engage in 'chemical warfare', but in a system containing allelopathic corals the benefits of carbon cannot be denied).

Other corals (many of the SPS's, etc) do best in nutrient free environments (carbon use being recommended as part of their care, with any trace element removal being counter-acted by typical dosing associated with their care due to the consumption rates of these corals).

However, certain corals (goniopora, alveopora, and various soft corals, etc) originate from and are suited to turbid environments and tend to fair better in nutrient-rich skimmer-less/carbon-free systems.

...I don't see how any micro or macropores can remove much of anything since water takes the path of least resistance. So between going through a pellet and around it the water will go around it...


My understanding: (i.e, I may or may not be correct (blush) )

Much of the 'removal' takes place at the molecular level via adsorbtion and ionic interaction. The media merely has to be in contact with the water for adsorbtion to occur. Since water takes the path of least resistance the carbon in the center of a carbon media bag probably isn't performing as efficiently as the carbon media in direct contact with the water flow. Even when the path of least resistance is taken into consideration, removal still occurs due to the properties of adsorbtion (in the meds removal role, as an example, med removal occurs, maybe not as efficient as it possibly could be, but it occurs never the less).

One could enhance the efficiency of each an every carbon particle (regardless of media shape) by running carbon in a reactor (basically forcing water through all of the carbon rather than through or in contact with just some of it).

[ILuvMyGoldBarb]

Here fishguy, read this
[Only Registered Users Can See Links.]

[Fishguy2727]

I am glad you brought up bags. This is a big problem with loose medias like carbon. Bags basically hold all the media together in the middle of the media tray. Water takes the path of least resistance, so in many cases (with certain types of bags and when not crammed into the media tray) the water simply goes around all that high end media you just bought.

Yes, Seachem says that the rod-shaped pellets are inefficient, but they have to, their product is spherical. I just don't think there is a huge different between sphere and elongated sphere, the water can easily get around. Their carbon seems better, but I don't think the pelleted carbons are as bad as they want them to be.

One issue I see is how to set it up. As stated bags can be a problems and it seems this carbon is too small to keep loose in a media tray.

Some of the more advanced keepers and books are now recommending short term periodic use of carbon (like a few hours once a month). This way bad stuff is removed, but the good stuff isn't removed all the time.

I am glad you brought coral warfare. Yes, in tanks with these types of corals carbon can be very important.

The other company I was trying to think of earlier was not a no name company, it is HBH.

[Wild Turkey]

Some of the more advanced keepers and books are now recommending short term periodic use of carbon (like a few hours once a month). This way bad stuff is removed, but the good stuff isn't removed all the time.

I use a similar method on my fw tanks. Every once in a while i'll load up a hob with carbon and give it a day on each tank then discard the carbon.