Filter Question

[poohbear1]

Ok setting up my new tank with an external filter do I need to keep the baskets with carbon in the filter or should I take them out

 

[JenCliBee]

u dont need the carbon in the tank it's usually just used 2 clear tank of any medications that may have been used


jen

 

[ox5477]

It wont hurt if you leave it in, it wont hurt if you take it out. Heres are soem pros for both situations:

Leave in: will help keep water more clear, removes mild "fishy" smell from tank, extra nooks and crannies for bacteria to grow on

Take out: reduced losses (increased flow) in filter as less flow restriction through the media, can medicate tank without having to worry about the medication being absorbed by the carbon

So, I would just leave it in unless there is a real reason that you don't want it in there, it will do much more good than bad.

Ox

 

[JenCliBee]

It wont hurt if you leave it in, it wont hurt if you take it out. Heres are soem pros for both situations:

Leave in: will help keep water more clear, removes mild "fishy" smell from tank, extra nooks and crannies for bacteria to grow on

Take out: reduced losses (increased flow) in filter as less flow restriction through the media, can medicate tank without having to worry about the medication being absorbed by the carbon

So, I would just leave it in unless there is a real reason that you don't want it in there, it will do much more good than bad.

Ox

wouldnt it release wot ever its caught in a couple days if it was left in carbon doesnt last long usually 24- at most a week then releases everythink back into the tank maybe causing alot more grief than just taking it out in the 1st place


jen

 

[ox5477]

I didnt think so Jen, but maybe... chemical stuff isnt my fortee... def a hands on mechanical guy
Ox

 

[TwoTankAmin]

That is an urban myth- the carbon will not release stuff back into the tank.

 

[Gatorbait]

Carbon won't leech back into your aquarium as it adsorbs not absorbs organic pollutants/chemicals. Bacteria that uses the carbon to colonize will also consume this waste.

Activated carbon will absorb gases but as it does it nuetralizes it so if it leeched what it absorbed it wouldn't be a problem.

The last proces of activated carbon is called chemosorption where matter is irreversibly bound to the carbon itself so again, it won't leech.

As suggested above it is harmless to have carbon in most cases but if you have too much you can cause oxygen depletion and some carbon is known to leech phosphates.

In most cases carbon is only useful for 2-3 days and then it becomes inactive so not much of a benefit to going out of your way to buy it unless you need to have the chemical filtration.

 

[JenCliBee]

u learn somethink new every day

 

[waterdrop]

Excellent summary by Gatorbait - thank you! Interesting about oxygen and phosphates - I had not heard that before.

For poohbear1, then I think we still arrive at the same advice that is currently given most often about carbon here in the "New" forum: Carbon is a very useful chemical filtration media that is used to adsorb meds (after they have run their course), to adsorb tannins (yellow water from bogwood etc.) and to adsorb organic smells (as mentioned.) It is only effective for about 3 days and then is ready to be removed and tossed out. Gatorbait has covered the leaching issue above.

Carbon will indeed harbor our good bacteria, just like other media in the filter, but is not considered ideal for this purpose for two reasons: The main reason is that it is not as long lasting as ceramics or sponges, it tends to physically break down and crumble over time, eventually leading to various practical problems containing it and removing it. The second complaint is more minor - it just does not have surfaces that are as optimized for anchoring bacteria as these other purpose-built biomedia have.

So carbon (aka activated carbon, aka charcoal), for modern aquarists, is an item for the storage shelf, ready to be used but ideally not left in the filter during normal times. The valuable filter space it would take up is better used for more ceramic rings, ceramic pebbles or sponge, depending on the mechanical filtration situation. (so biomedia and mechanical media are always present, chemical media is swapped in for special situations)

~~waterdrop~~

 

[backtotropical]

That is an urban myth- the carbon will not release stuff back into the tank.

Carbon won't leech back into your aquarium as it adsorbs not absorbs organic pollutants/chemicals.

There is a thread in the 'Scientific Section' at the moment discussing the same topic. Here is a quote from Bignose

This is from an old thread (http/www.fishforums.net/content/forum/72100/Does-Carbon-Leak-toxins-back-into-water-/):

The chemicals that get adsorbed onto the actived carbon are in equilibrium with the tank water. The activated carbon will take up chemcials until that equilibrium is reached. What that equilibrium point is depends upon the concentration of the pollutant and how used up the carbon is already -- what percentage of the active spots on the carbon are still available.

Normally, when using carbon to take out medications for example, it will take up an overwhelming percentage of the chemicals. Say from 100% to 0.1%. What I mean is that 0.1% is the equilibrium. Now, you do a 25% water change. So, concentration of chemicals is now 0.075% in your tank. If you do not change the carbon at this time, the carbon will release some of the chemicals, again going towards equilibrium. Since, most of the chemicals are on the carbon now (99.9% of the original amount) given enough time (and this depends on temp, pH, etc.) the sysytem will tend toward equilibrium again. Meaning the carbon realeases 0.025% back into your water, to bring the concentration of chemcials back to 0.1% -- equilibrium.

Not a huge amount, but you see how a little bit can be released back. And long-term exposure, even at very low concetrations can lead to ill health.


Here is even a little more:

Lets call c the concentration of any chemical in the water that will be adsorbed.

If the adsorbtion at equilibrium follows the Langmuir isotherm (probably the most common -- there are others) the concentration of the chemical on the carbon, which I will call n is equal to:

n = c/(K+c)

K is the called the adsorption or equilibrium constant. It will vary depending upon what chemical we are talking about, and what quality the carbon is.

The total concentration of chemical is T

T=n+c

or using the definition of the adsorbed amount

T = c/(K+c) + c

Now, if we lower c a little (by doing a partial water change, for example) T does get lowered to T2, but so does n -- so call the new n2.

But again, T2=n2+c2 where n2=c2/(K+c2)

where does the difference adsorbed (n2-n) go? back into the water.

The carbon will uptake and release chemicals until equilibrium is reached, every time. So, yes, it is usually a small amount that will get released back -- carbon is very efficient uptaking chemicals when active sites are available -- but a small amount does get released.

My understanding from this is that carbon will leach some chemicals back into the water.

BTT

 

[ox5477]

well the only way chemicals will get into the tank if from u.... so if you just follow proper procedures during medicine or fertilizer dosing (usually say remove carbon while dosing) then you shouldn't have any worry. And in fact, you could just throw the carbon out if you have enough other mechanical filtration (sponges, ceramic media) and then no worries.

Ox

 

[TwoTankAmin]

Not all carbon is the same. From what it is derived and how it is activated is important.

Here is a quote from an article I found at the Chichlid-Forum.com Revisiting Activated Carbon

It is by Dr. Timothy A. Hovanec and is credited to Marineland which sells Black Diamond Activated Carbon:

DE-ADSORPTION

De-adsorption is another phenomenon that is over-stated in the rumor mills about activated carbon. Again, it is an incomplete statement that is commonly used to described the process. It goes, in one fashion or another, as: don't use carbon because once its adsorption sites are full it will release, or de-adsorb, all the stuff it has adsorbed releasing a large amount of pollutants back into the aquarium. The implication in this sentence that activated carbon works something like a capacitor such that once at its maximum adsorption capacity, it instantaneously discharges all the bad things it has adsorbed is wrong. Carbon does de-adsorb, in fact, that ability is exploited for recycling precious metals. However, in a controlled industrial process, the quick release of the target substance is accomplished by switching the pH of the water. The basic process is to capture the target substance at one pH extreme (very acidic or basic) and then reclaim the substance by switching to the other pH extreme. As stated earlier in this article, these pH values are outside the normal range of aquaria. De-adsorption is not a process to be worried about.

And this is what the article says about phosphate leaching:

PHOSPHOROUS

Phosphorous is another element linked to activated carbon. Some carbons leach phosphate into the aquarium water. The phosphate can be a naturally occurring part of the carbon or it can be from phosphoric acid which is used in the activation process. In either case, the phosphate is not toxic, rather it can contribute to eutrophic conditions in the aquarium water and may lead to algae blooms. If you are concerned about phosphates, switch brands of carbon. There are several bituminous coal-based carbons available from reputable companies that are phosphate-free.

This is what the Marineland site says about its Black Diamond Activated Carbon:

Black Diamond®
Black Diamond Premium Activated Carbon eliminates discoloration, odors, and impurities...and keeps on doing it long after other carbons quit.

Heat-activated bituminous coal-based Black Diamond granules are specially sized and far more efficient than inferior coconut, wood or peat-based carbons. Premium Black Diamond works as much as twice as fast as the competition.

So either the above is wrong, or using a bitumionous coal based carbon that is heat activated rather than chemically activated means no phosphates are leached and de-adsorbtion is not a factor in an aquarium due to the extreme pH level changes needed to make carbon de-adsorb.

 

[waterdrop]

I too have read articles about how carbon is not carbon is not carbon. Carbon (aka activiated charcoal) can indeed be made from very different materials and by very different processes with no doubt a fair difference in results. Aquarists who need to use it on an extended basis then would do well to study these differences if they can.

But I think the above post just gives us all the more reason to generally recommend that carbon not be used on by average aquarists on an all-the-time basis. Yes, it should be on the shelf. And the easy thing to remember is that it is good for 3 things: removing medications, removing yellow tannin stains from wood introductions and finally, one-time removing of organic smells such as fish that died during vacation or other unusual events.

Note that I'm saying "average" aquariums. I'm not saying there is not a place for an advanced aquarist to find a very good charcoal product and decide that it helps clear up certain recurring things in his/her tank and that he/she can afford to change it out every week. That's fine I would think. I just think that in most normal cases its a better recommendation to the beginning and average fishkeeper to use that extra volume in the filter for sponge or ceramics and leave the carbon on the shelf. Oh, and I agree with ox that this is not such a big deal that there is anything very wrong with leaving in carbon you've already got before thinking about all this - it can be gradually changed out later.

~~waterdrop~~