What are the effects of using activated carbon?

[iwishweallcouldwin]

I would like to ask about the effects of adding activated carbon into the tank. I heard that it helps to remove toxics caused by mass death and medication, and also helps to reduce yellowing of water by removing tannic acid from driftwoods' leeching.

This isn't good for apistos I presume? Since removing tannic acid means that the pH of the water will rise? Could that be the reason why my apistos' bodies turned darker? Also, does activated carbon remove nitrate and ammonia?

[illumnae]

i have activated carbon in my filter and my ph remains at 5+ so no worries on that account. i personally like activated carbon in my filters as it keeps the water clear and helps remove toxic chemicals. however you must remember to change it every few months to keep it effective.

some people like to say that carbon is bad because it releases the chemicals back into your water once it's "full", but based on chemistry, the horror stories you hear are not true.

however, if you are intending to plant in the tanks and dose ferts, or if you want to medicate your fish, then removing the carbon is the way to go, otherwise your ferts/medicine will be absorbed and ineffective, and your carbon will get "full" sooner

edit: this discussion on carbon is OT...would be good if a mod could kindly split it off please?

[luenny]

some people like to say that carbon is bad because it releases the chemicals back into your water once it's "full", but based on chemistry, the horror stories you hear are not true.

Just want to say that this is very true. Activated carbon can lek chemicals back when it is full. That is why it is extremely important to change it regularly!

[illumnae]

i disagree. the reason why carbon can "soak" up chemicals is because it reacts and bonds with them. once the chemical reaction occurs, a new (usually inert) compound is formed, and it won't revert back just because there's no more carbon to react. it'll just be a useless mass and not harmful.

[stephen chung]

The only reason I can think of is, active carbon comes from different manufacturer and thus they behaved differently and so is the water chemistry. Every tank's water chemistry is different.

So, some just like what illumnae says it just soaks up and change it into inert compound and some might change into something toxic..

I just guess...

[Quixotic]

Actually, it is probably yes and no, depending on the quality and type of activated carbon being used.

An interesting article about activated carbon in the marine tank, probably no different from a planted tank, including how adsorption works.
http://www.hallman.org/filter/gac.html

...The carbon product may be supplied as granular activated carbon (GAC), powdered activated carbon (PAC), or in pelleted form (compressed PAC). Some carbons are activated or washed with phosphoric acid, zinc chloride, or potassium hydroxide. These chemically treated activated carbons are unsuitable for use in the aquarium. These products could leach phosphate (an algae promoter), heavy metals, or alter pH...
...Nine activated carbon products were tested for phosphate contamination. Five of these contained phosphate, including so called “marine” carbons...

Also, articles on Wikipedia...
http://en.wikipedia.org/wiki/Activated_carbon
http://en.wikipedia.org/wiki/Adsorption

The process by which activated carbon works is via adsorption. The "contaminants" are adsorbed primarily via physisorption (physical adsorption) but can also happen via chemisorption (chemical adsorption).

Because of the physisorption process...

...In theory activated carbon could release or desorb what it removed at some point. But practical experience with aquarium filtration and laboratory experiments show desorption rarely occurs or causes any type of “toxic release”...

I think the fact that there are different grades and not all activated carbon products are equal in performance, confuses the usage in the aquaria, especially when aquarists have "bad" experiences with them.

[luenny]

Thanks Quixotic for saving me to search for the explanation and articles again. And oh, if you think that all activated carbon soak up chemicals and hold it forever, how come there are some activated carbon manufacturers that claim their activated carbon can be "recharged" by soaking in hot water to release the chemicals absorbed?? I'm just saying that better be safe than sorry unless you really know the make of your AC filter. It is possible that chemicals leak back and if you really want to use it, be sure you change your AC filter regularly.

[Quixotic]

This isn't good for apistos I presume? Since removing tannic acid means that the pH of the water will rise? Could that be the reason why my apistos' bodies turned darker? Also, does activated carbon remove nitrate and ammonia?

Now, coming back to these questions. There is no need to be overly concerned about the pH. The pH may rise, but I doubt it would cross over to the alkaline boundary.

Fishes can live within a range of pH, and most are okay with pH close to neutral (= 7.0) either side. Apistos generally have no problems with pH close to neutral. In my opinion, pH fluctuations, rather than keeping fishes in non optimum pH conditions, are more of a concern.

Wikipedia entry metioned that AC does not bind well to certain chemicals, including ammonia. I take it that "does not bind well" means, some minimal binding does occur but AC removes them at very minimal quantity. Some literatures also mentioned that AC does not remove nitrate at all.

So, rather than contemplating if AC could remove them, use what has been proven, i.e. plants to remove ammonia as they are the natural absorbers, and water changes to remove nitrate.

[iwishweallcouldwin]

hi all,

thanks alot everyone, especially quixotic, for shifting the thread to a more appropriate section and for all your very useful and detailed answer regarding my query. indeed i have benefitted alot.

guess i'll continue to use activated carbon for my planted tank, and continue with my twice a week 10-30% water change regime. but will make it a point to change the packet every month!

thanks alot once again!

[sithspawn]

So what would be good brands of Carbon to buy from everyone's experience. I've just bought Mr Aqua Carbon and Bamboo carbon as well to try out. I'm inclined to use Seachem products most of the time but i'm planing to try out purigen as a carbon replacement.

[Quixotic]

I am not concerned about the use of AC in my tanks, so I can't tell what is generally good.

Did you read the document in one of the links I posted? Some guideline specifications are provided in there, the last section of the page. Although it applies to marine setups, I would lean towards the idea that it should not differ much from freshwater setups.
http://www.hallman.org/filter/gac.html

I am not sure though, if the AC products available here provide their specifications enough to make an educated choice. *shrug*

[BFG]

In my humble opinion, for AC issue, is that it is best if you could change it frequently. Also, buy in bulk as it is cheaper in the long run. For me, an activated carbon is an activated carbon and I usually replace mine monthly.

Worst part of buying in bulk is washing off the fine soot.

[minx]

Thanks Quixotic for saving me to search for the explanation and articles again. And oh, if you think that all activated carbon soak up chemicals and hold it forever, how come there are some activated carbon manufacturers that claim their activated carbon can be "recharged" by soaking in hot water to release the chemicals absorbed?? I'm just saying that better be safe than sorry unless you really know the make of your AC filter. It is possible that chemicals leak back and if you really want to use it, be sure you change your AC filter regularly.

luenny,

for AC to recharge it needs "hot" water and I do not foresee any tanks with livestocks with such high temperature in the near nor distant future. Thus, leaching of chemicals adsorbed is practically nil but as you say "better be save than sorry" if you are unsure about the products you are using.

[BFG]

Found this link while surfing in a foreign marine forum.

http://www.pets-warehouse.com/carbon.htm