# [Wet Thumb Forum]-Activated carbon



## ScottH. (May 13, 2004)

I have activated carbon in my filters and I was wondering that if this stuff is supposed to take out harmful things in the tank than is it taking out good, helpful things such as Fertilizer?

My goal is a sea of green.


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## ScottH. (May 13, 2004)

I have activated carbon in my filters and I was wondering that if this stuff is supposed to take out harmful things in the tank than is it taking out good, helpful things such as Fertilizer?

My goal is a sea of green.


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## wetmanNY (Feb 1, 2003)

Well, first of all, do we all agree that we're talking about the action of granular activated carbon only in the first 48 to 72 hours of its career in the filter? After that most of its effect, for good or bad, is spent.

The best articles describing activated charcoal were written by Tim Hovanec, for _Aquarium Fish,_ May 1993 and again in June 1998. (There was a further recap in the June 2000 issue.) Though none of this matter was archived at the Aquarium Fish website, you can find condensed versions of his two carbon articles among Hovanec's library at the Marineland website: www.marineland.com .

Those versions didn't reprint Hovanec's useful table of what activated carbon adsorbs well, moderately, only fairly, or not at all: the table is reproduced at the Discus-L mailing-list site: http://world.std.com/~enjolras/discus-l.html Click on "Carbon-- good or bad?"

Hovanec's assessment of carbon's adsorption of complexed copper and ferric iron is only "fair." I can't square these two assessments, but I feel that no one arguing about adsorption of desirable trace elements seems to have looked at this table.


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## Roger Miller (Jun 19, 2004)

There's an interesting article at the Krib that you may be interested in.

http://www.thekrib.com/Plants/Fertilizer/keslar-carbon.html

It has actual data!

Roger Miller


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## jpmtotoro (Feb 13, 2003)

enlightening articles, thanks both!


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## wetmanNY (Feb 1, 2003)

For those who don't follow up links, chemist Shawn Keslar put a measured amount of Plantex CSM trace element mix (containing magnesium, manganese, copper, zinc and iron-- all in chelated forms-- and non-chelated molybdenum) into de-ionized water, then graphed the levels of trace elements in the solution over a period of 96 hours, compared with a control sample. Simple and nice!

Keslar found only that chelated iron and chelated manganese were affected by fresh activated carbon. Other micronutrients were not.

Since it's generally agreed that granular activated carbon adsorbs chelating organic molecules and artificial chelators such as EDTA, it's natural to ask whether it isn't the chelating molecule that's actually being adsorbed by the carbon, rather than the metal ion.

And to ask whether-- since the ionic state of these metals is actually the only effectively bio-available phase-- the micronutrients aren't just as available for release to plants from the chelation when the chelator is adsorbed to carbon-- or any other substrate?

Re: manganese. If you have _ever_ in the life of your system used potassium permanganate for any reason, there is sure to be enough manganese-- as manganese oxides-- in the system. It's not the presence of these micronutrients-- it's the chelation that counts.


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## ScottH. (May 13, 2004)

hey thanx for those links. Those sites were rather interesting. So should I dose more to keep the iron, manganese levels up?

My goal is a sea of green.


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## wetmanNY (Feb 1, 2003)

_"...it's the chelation that counts."_


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## imported_aspen (Feb 20, 2003)

if only one micronutrient is adsorbed by carbon, this is enough to cause your plants not to grow isn't it? 

a 'sea of green' will become a 'sea of transparent new growth' in 1 - 5 weeks depending on growth rate of the plants.

i don't use carbon. what is it good for that water changes won't do?

rick


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## chbak014 (Feb 3, 2003)

you have to becareful with carbon. some carbons leech out phosphates. like in my case, phosphate leached out and i didn't have enough nitrate in the tank. basically, plants stalled growth and i have a bad case of green water right now which i am treating with a 3 day black out followed by a 50% water change.
-charley

http://www.geocities.com/charleybak/aquarium.index.html

http://www.pbase.com/chbak014


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## wetmanNY (Feb 1, 2003)

Surely carbon that leaches all but untestable amounts of PO4 is widely available, is it not? Greg Schiemer tested quite a few activated carbons for the amount of phosphate they leached (all carbons do leach some). The results are edifying. They were in _Aquarium Frontiers_ in 1997 archived at: http://www.animalnetwork.com/fish2/aqfm/1997/jul/product/default.asp

Leo Morin, of Seachem, had some interesting contributions about phosphate and activated carbon a few years back: his interview with Bruce Hallman is at http://www.hallman.org/filter/carbon.html

There's a fundamental inconsistency here: having avoided activated carbon because it leaches undesirable phosphate on a Monday, one could take out the Fleet enema on a Tuesday and squirt a little urgently-required phosphate into the system...

[This message was edited by wetmanNY on Sun March 23 2003 at 09:21 PM.]


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## imported_Allen (Feb 14, 2003)

Hmmm... I must say that this has been interesting to say the least. I myself have always avoided the use of activated carbon because "it would bind nutrients"... but these articles are forcing me to rethink this...

You do bring up a good point on the test done by Keslar... was the the carbon acting on the chelates or the ion itself... was there any follow up done? I couldn't find any...

Allen 
============
Allen's Tank Pics.
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