Is there a reason why I should NOT use carbon in my filters?

[DeadStang]

My friend told me it is not what people do anymore and I was advised by my LFS to use it.

[AllFishNoBrakes]

@DeadStang I’ve never used it. Do you plan on having plants and using fertilizer? If that answer is yes, the carbon will pull the fertilizer out of the water and you’ll be fighting against yourself. 
 

The only reason I can think of to use carbon is to pull things out of the water. Meds, toxins (like if I was staining my hardwood floors or something), etc. 

Edited March 16, 2023 by AllFishNoBrakes

[Cinnebuns]

There is reasons not to. Mainly, it needs to be changed out periodically. If you don't, it can leech whatever it absorbed back into the tank. If you are on top of changing it as needed feel free to run it. Some people do. 

It is however true that most people in the hobby do not run carbon on a regular basis but only as needed. It can be used to pull things like medicine or other things out of the water. 

[Lennie]

Here you go:

 

[Andy's Fish Den]

Back 20 years ago, everybody ran carbon in their filters, but it has gone by the way side. As someone else mentioned it was found that if it is not changed regularly, it will slowly release whatever it has absorbed back into the tank. And, if you have a planted tank and using fertilizers, it will pull those ferts out of the water column. The only time I use carbon now is if I want to absorb any medications out of the water, and I use it for a couple days and pull it out. 

[Mmiller2001]

It's a waste of money really. Purigen is better and can be reused many times.

[Andy's Fish Den]

On 3/16/2023 at 7:12 AM, Pepere said:

What exactly does it pull out for fertilizer?

 

does it pull out nitrates?  Or other things like potassium, phosphorous etc?

 

have there been studies quantifying what percentage of what fertilizer components it pulls?

No idea, I am not a chemist or whatever kind of scientist that would know. Carbon removes chemicals from the water, so, whatever chemicals I guess. 

I also know that there have been studies that have linked it to hole in the head disease in marine fish such as surgeonfish. Last I heard, they had not done a study on FW fish since there are some kind of cichlids that will get HITH as well. Carbon had been used for years in reef tanks to help with purifying the tank water.

Edited March 16, 2023 by Andy's Fish Den

[lefty o]

On 3/16/2023 at 9:32 AM, Pepere said:

My understanding is that carbon pulls out larger organic chemicals.

I believe it pulls out Chelated Iron, but most components of total fertilizers are relatively unaffected.  But if anyone has specific knowledge to the contrary I would love to know..

Mostly I use carbon in quarantine tanks after running meds.

 

from time to time I run it in a display tank if the wateris getting a yellowish or brownish cast or an off odor.  Mostly though, water changes keep that in check…

carbon is pretty much like a sponge, it will absorb just about anything with the catch being it will only do so for a short time before it is full. i am a carbon user, but it is absolutely not needed for day to day tank use. it is just an aid in fish keeping, not a cure all for poor tank keeping.

[Mmiller2001]

On 3/16/2023 at 7:52 AM, Pepere said:

Recharging Purigen entails some expense too. 
 

a cup of bleach is $0.30.

2 ounces of prime is $0.50.

A 1.7 ounce package of Purigen costs 11.50 and can be  recharged 10 times

 

figure about $1.50 - 1.80 a recharge between product cost and recharge chemical cost.

Activated carbon can be had for$16.00 for 40 ounces.

$0.40 an ounce

I will have to weigh out how much I use in my box filter tonight…  shooting from the hip, my guess is 2-3 ounces.

activated carbon lasts about a month.  It makes wonderful soil amendment after being used up.  It is not plastic like Purigen..

 

I had Purigen,  recharged it a few times and then just tossed it.  More hassle than it was worth…. Worrying about residual bleach etc….  Seachem also reccomends using their neutral regulator after dechlorinator too..The tiny beads would leak out of the microfine bag pores too…

I bought 1 40 ounce jar of Activated Carbon in March of last year.  It is still over half full..  I suspect Purigen is not any cheaper to use.

Activated carbon only really works for 3, maybe 4 days.

[NOLANANO]

If you have plants, I have read that it sucks up nutrients that the plants need/could use.  If you have fake pants, I think its fine to use but not necessary.

[Guppysnail]

Yes. Replacing it every 3 weeks gets expensive and you are throwing away any beneficial bacteria that may have grown on it. I use sponge media in my hobs and canisters. 

Edited March 16, 2023 by Guppysnail

[Colu]

I only use it to remove medication if your have enough plants and keep on top of maintenance you shouldn't need to use active carbon 

Edited March 16, 2023 by Colu

[rockfisher]

First I see all these links and things in fish forums and by aquarium product makers that say Carbon does not remove N of Ph and many of the other nutrients we rely on to grow plants. Im not sure where that information comes from. It is often used in fertilizer spills to help remove those exact things from the spill areas. It is also one of the most impactful ways to remove them from effluent water. The only reason I can think that they say this is because  the amount of carbon most people in an aquarium filter is so small and last for such a short time before the small amount has to be replaced. I don’t use carbon much. I do use at times when a black water tank gets way to dark. I use carbon then. It takes a good amount of carbon a di have to change it daily for it to keep removing  tannis. Carbon basically grabs many chemicals from the water and hold the with ionic bonds. It does a great job at grabbing nitrogen phosphate along with many of the  Mirco nutrients. I would not use charcoal on an every day basis due to this.

[rockfisher]

The reason carbon was added by ancient indigenous people was to help hold the nutrients in that soil. It’s probably a good in a pot as it would hold nutrients but it would also hold heavy metals as well.  I think the use in your tank is spot on.  Not that it really matters what I say. 

Edited March 17, 2023 by rockfisher

[Rewcolee1]

I’m truly having a mind blown moment right now. I’ve had aquariums of various sizes, with all different types of fish over the past 30yrs. I have never had an aquarium that doesn’t have carbon in it. I was told to use it when I started and never had a 2nd thought from that point. I guess now I’ll have to do some serious research.

 My canister filter current consists of sponges, 2 bags of carbon, Fluval ammonia remover and clear max. I do have a planted tank. So if I’m following along here I should be able to remove the carbon and I would be no worse for the wear and potentially better off since carbon may remove fertilizer from the water column . 

[DeadStang]

I appreciate everyone's replies on this topic. Obviously, the carbon-in-my-filter suggestion came from an "old time"fish keeper and the long-time owner of my LFS according to what I am seeing here. I did watch a portion of Cory's ACO video (it was long and very good but I ran out of time -- I'll finish it this weekend). From the responses and from what I gleaned from Cory's video, carbon is a good thing in some situations, very likely mine specifically.

I have an old shallow well (28' deep) in a rural area surrounded by land that's been field-farmed extensively for probably 100 years. In the summer, the nitrates are 40ppm from the tap but as the rainy season has stretched on for 6 months, it seems the old fertilizers and such leach into the groundwater and thus into the water table that feeds my well. The nitrates are running maybe 80ppm from the tap now. I am using nitrates as the measure of "stuff" in my water.

I have a 29 gallon community tank that has been doing great, and with my generally high, stable nitrates, my plants (in the tank and the pathos and such that hang out the back) are doing really well. I use the Easy Green once in awhile (monthly at most) but don't really seem to need it. 3 weeks ago my Apistogramma cacatuoides (I had 3 of them) starting acting weird, hiding and not eating. At first I assumed they were exhibiting breeding behavior as they had been displaying and guarding a little hidey-hole "territory." Anyway, the male and a female ended up dying, to my extreme unhappiness. I took the male into my old guy LFS and we did a necropsy of my little buddy. Ultimately, he did not have fatty liver but his liver was pale and abnormal, and his gills were trashed with little absorptive capacity. There was no ich and zero evidence of parasites. I test my water literally daily with zero ammonia or nitrites, a pH of 7.4-7.6, and the stable, moderately high nitrates.

The diagnosis was "unknown toxin," and he suggested carbon in my filter, which I immediately went home and added. He said that the Apistos can more more sensitive to toxins in the water than other fish, whichis why only they were affected. All other fish are 100% fine (corys, hatchets, a couple gouramis, rummy-nosed tetras, and some little flame tetras).

So my conclusion is that, along with old fertilizers (=nitrate)s, some other ground chemical(s) leached into my well and killed my special fish. Alternately I may somehow have inadvertently introduced something into that tank, but I am pretty careful washing my hands and rinsing or soaking everything I use. But I think using carbon with monthly carbon changes is probably a good idea for my situation. As a side benefit, I thought my water was very clear and the tank looked good, but the morning after I added the carbon to my HOB, the water was shockingly clear and beautiful, and the tank looked fantastic! My cycled-but-not-seasoned tank has had some algae issues (as expected), and the carbon cut my algae problem at least in half, virtually overnight, as well. So I am sold on using it in my situation.

 

Edited March 18, 2023 by DeadStang

[AllFishNoBrakes]

@DeadStang Makes sense to me! This is the prime example of “the whole picture actually paints 1,000 words”. If my tap/well water was like yours I’d probably use Carbon, too. Thanks for sharing with us. 

[Rewcolee1]

Well. I’ve ordered Purigen. PetSmart has an awesome deal right now. Buy 1 get one 50% off. I’ve read enough that I feel pretty confident making the switch. I have city water and it should take the place of multiple items in my canister filter.

Edited March 18, 2023 by Rewcolee1

[Rewcolee1]

Yep, I ordered 2 of those. They were also buy one get one 50% off.