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Discussion Starter · #1 ·
Just got back in the hobby after a brief hiatus. Great to be starting a planted tank again and have a quick question. Something I'm sure I have addressed before but alas must ask this question. Have a 90 gallon and am planting heavily and have an xp2 canister with sponges only at the moment. Wondering if activated carbon is ok or useless or..??? Thanks all.
 

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Activated carbon does work, but it looks like very few planted tank keepers use it routinely. If you do use it, you will have to replace the carbon every week or so, because it only works for a short time in a typical aquarium.
 

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Discussion Starter · #3 ·
Thanks for quick response. Every week? Never heard of that before. Does it strip out what the plants require to any degree? If one needs to replace it every week, well not much sense in using it I figure. I do have some purigen left over from last setup, so maybe put that in the filter. I have read lots of people using that, and if I remember I did also to some degree.
 

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Carbon is effective only on large molecules, organic molecules, and our fertilizer chemicals are all very small inorganic molecules, except for the chelators in trace mixtures. For that reason it won't remove nutrients from the water.
 

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Carbon is effective only on large molecules, organic molecules, and our fertilizer chemicals are all very small inorganic molecules, except for the chelators in trace mixtures. For that reason it won't remove nutrients from the water.
Hoppy,
after the couple weeks, doesn't carbon just become a source for biological filtration with enough porosity to support bacteria colonies?
 

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@IUnknown yes, but at some point they satiate and then things become unpredictable. I don't think you need to chuck it weekly. Yes maybe at the start, when there are lots of large physical particles in the water, but the longer your tank is clean the longer it can go... I don't use it for planted tanks, but for my fry tanks, and swap about every two weeks. most of the larger tanks have two filters in, so I do only one at a time to keep bacterial levels more stable.
 

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How long the activated carbon is effective depends largely on how much you can fit in the filter.
Given how little of the carbon is found in most cartridges for HOB filter's,I too think a week ,maybe two before it would be exhausted.
Maybe a little longer in canister if bag/pouch is larger.
Purigen would be maybe better choice ,for it can be recharged four or five times IME.
Have not heard or experienced activated carbon increasing the pH.
Activated carbon cannot release what it has collected through ADsorption(different than ABsorption) unless subjected to temp's not achieved in the aquarium.
Once it has Adsorbed all it can,it then just becomes media for bacteria to colonize same as anything else in the filter.
 

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Discussion Starter · #9 ·
Basically there is nothing detrimental to using it , it seems. Same as any freshwater tank. Once it is exhausted, just replace it. I have not heard of AC raising pH. Seems using it can be expensive. I think I'll just use some purigen combined with sponges and a polisher. Thanks all.
 

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If you use liquid fert. the carbon will absorb whatever you add to the tank. Personally I only use carbon bag if I had to treat a tank and than remove that treatment or if the water looking murky, as will as very six months as a preventive measure, from the tap water.. Carbon filter will only absorb as much chemicals as it can hold, and than start leaching back into a water, like a sponge. I use a good carbon about 3 to 4 cups poured in a bag and just place that in the filter for the month, when I do my monthly filter break downs. I find it cheaper to buy loose carbon, than buying premade pads.
 

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If you use liquid fert. the carbon will absorb whatever you add to the tank.
It is possible to make activated carbon that can adsorb small molecules, but aquarium carbon doesn't do so. Aquarium carbon is very cheaply made.
Personally I only use carbon bag if I had to treat a tank and than remove that treatment or if the water looking murky, as will as very six months as a preventive measure, from the tap water.. Carbon filter will only absorb as much chemicals as it can hold, and than start leaching back into a water, like a sponge.
I don't believe this is true. Carbon is not a sponge.
I use a good carbon about 3 to 4 cups poured in a bag and just place that in the filter for the month, when I do my monthly filter break downs. I find it cheaper to buy loose carbon, than buying premade pads.
 

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Hoppy, think about a carbon filter attached to your drinking water either on the sink or even in you refrig. water dispenser, the filter is only good for few months (read the box, this is a high grade of carbon) than it no longer absorb the contaminates, the carbon is full. starts leaching back into you drink glass, hence the taste difference between an old filter and a new drinking water filter. If you do not think I'm correct than please site some information that i have not read i know new information is discovered. Been keeping fish starting in the early 80's,I do not wish to spread incorrect info'
 

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The reason we use carbon filters on our drinking water is usually because the water tastes bad if we don't. When the filter is maxed out and can adsorb no more, the water again tastes bad, not because the filter is leaching anything, but because it isn't adsorbing anything. Doesn't that make a lot more sense than having the filter suddenly shift from adsorbing to leaching, which would then open more space for the filter to begin adsorbing again? If my logic is faulty then you could be right.
 

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General carbon for the aquarium industry typically only has an effective use of 6 days before it is exhausted according to past studies. It is also being more, and more linked to HITH. I see it only usefull if you have a specific reason to use it. I've been carbon-less for years, never a issue.

The theory of leeching lends itself from the carbon breaking down to smaller sizes from use, re-entering the water volume. At least the way i look at it. To be bound to the carbon, and removed opposed to being kept in use, dwindling away via erosion.
 

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I use a little carbon in small pouches when I clean/change my filter media and sponges.

I think it helps the water look crystal clear and acts as bio media once the newness wears off.

I'm not a big believer that it dilutes the nutrients in the water column unless you're turn over rate is like 10 times per hour or something..
 

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For me Carbon has it's place in new setups where the bio-filter and/or plants aren't strong enough yet. It bridges the gap until the bio-filter matures. It's also helpful in sparsely planted setups that require higher light due to the tanks depth and/or the plants your growing. It's just another tool to remove organics that might cause algae.
 

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I always use activated carbon in all my tanks, which are all planted, except when needing to medicate. I bought the replacement bags in bulk on Amazon and replace them once a month. Also in addition use Purigen as well. Worth to note that seachem recommends never letting Purigen completely dry out. I only say since you mentioned having some left over.
All tanks develop an odor over time. Like any other scent people become used to the smell and may never notice it. Others enjoy the earthy smell. I am not one of those people and also appreciate the water clarity that activated carbon provides.
 

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I think we are get to the same end point. I originally used a sponge as a common visual, carbon is a pours like a sponge under a micro scoop, which allows it a absorb, we agree om that. however you disagree that once the carbon is full it will not can absorb any more, it is saturated and as new water flows by it the carbon just holds what it has collected. I contend that if you take a saturated sponge full with red died water than place it in a container of clear water. The sponge does not hold the red dye, it slowly leaches into the clear water, this is without any water flow. Add a water circulation and it will very quickly turn the water red. In an aquarium use, let say you a treating the tank, you put the carbon in your filter to remove what ever solution you had to add. next week you do your WC but forget to remove the old carbon. You add new water but your tank still have the solution in the water, it a smaller Ppm but it still there. that is caused be fresh clean water passing thru the old carbon leeching back out.

I was really just try to answer the post as to when and how to use carbon effectively in a planted tank, not debate, my use of the word leaching.
 

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For the OP, I use the Activated Carbon for the first 2 weeks of an aquarium then remove. I also add at the end of a treatment, otherwise put your money elsewhere.
@djrichie while experience is to be respected, length of time one kept fishes has little correlation with the amount of knowledge one has (one person who keeps guppies for fun for 25 years vs. a PhD on Aquatic Sciences doing research in aquarium topics for 5 years)

Just to clarify, a sponge aBsorbs water. Activated carbon aDsorbs large organic molecules. Understand the difference between the 2 and you will see how @Hoppy is right. Because the carbon aDsorbs, breaking down to smaller pieces does not release the molecules.

Desorption (NOT leaching nor lynching) is possible but will not happen at any significant rate under the conditions present in the aquarium ( in industry it is used to recover substances). Desorption is done using sonication, very high temperature, pressure, pH swings, electrodialysis or strong solvents (again outside normal aquarium ranges)

Activated Carbon will not reduce the concentration of EI or standard liquid fertilizers. Maybe interact with chelators ???


More infomation on aDsorption, and substaces Activated Carbon interacts with are here:
Adsorption / Active Carbon

Info on desorption can be read here (paywall):
Adsorption and desorption of phenol on activated carbon and a comparison of isotherm models

And a easy dissertation on desorption here:
https://books.google.de/books?id=A1...ctivated carbon desorption conditions&f=false
 

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ok i will take my 25 years of guppy keeping, and all the books, and mag subscriptions information i collected over the years and leave... I forgot how forums work. thanks for the info and the insult, there dukydaf. I raised and have breed fish for 25years, I never had any guppies. FYI
 
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