Tropical Fish Keeping - Aquarium fish care and resources

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frmrgrl87 01-24-2010 04:41 PM

activated carbon filters
Hello all, I am new here, and relatively new to serious tropical fish keeping. I have an AquaClear 50 filter system. For those of you who are not familliar with it, it has three different filtering parts, a mechanical (sponge) phase, a chemical (activated carbon) phase, and a biological (good bacteria) phase. I was just wondering how long the activated carbon was "good" for. Also was thinking about switching to an alternative chemical stage to remove excess nitrogen. Any thoughts or comments would be appreciated.. Thanks!

Angel079 01-24-2010 06:24 PM

I'd take it out period. There's no necessity for it unless you're medicating the tank for some reason. On top if you have plants in there or even use fertilizers for them its actually less then ideal.
So if you ask me -a plant fan- take it out :-)

Oh and Welcome to our Forum; just seen your hassle-move answer from TX to NY with a bucket....what a headache that must have been for you; sure glad to hear all are fine :-)

7yl4r 01-24-2010 08:24 PM

From the reading I've done I've opted for no chemical filtration as well. I think that as long as you do regular water changes there is really no need (in most cases).

JohnnyD44 01-24-2010 08:31 PM

what do you mean by chemical filtration?? you'll still need weekly doses of water conditioner when you do your pwc....

MOA 01-24-2010 08:32 PM


I have researched filtration in aquaria quite a bit and I have found very little reason to use activated carbon, zeolite, or any chemical filtration in an otherwise healthy aquarium. You are probably going to spend more on these things than they will ever make for you (I have never seen these products make the difference in saving a fish's life or in preventing major problems).


P.S., If you want to read more about what influences filtration, you can either do a search on this site (using the "search" function at the top) or you can click on my sig.

Pasfur 01-24-2010 09:01 PM

I am always confused by this debate. Activated carbon absorbs acids and organic waste. The acids deplete carbonates, resulting in a less stable pH, and stress to the fish. Organics break down into nitrate, requiring larger and more frequent water changes. Clearly carbon has benefits.

Now, if you make the assumption that this is a live plant tank, then this argument changes and I understand why carbon would not be used. But if this is just your average freshwater system with plastic plants and artificial decorations, then I think activated carbon is extremely useful.

MOA 01-24-2010 09:15 PM


Carbon does not absorb all organics and it does not typically absorb those responsible for the creation of nitrate. The safest, most reliable, most natural way to process organics in a freshwater aquarium is to make use of beneficial aerobic bacteria. As to any fluctuations in pH, most fish are very hardy and pH instability due to organics typically only occurs in tanks that are overstocked and have a very low alkalinity. Another thing to note is that some chemical purifiers can inhibit proper cycling (especially zeolite). Essentially, if your preform regular water changes and avoid overstocking, then carbon simply isn't needed.


iamntbatman 01-24-2010 09:47 PM

I happen to be on the carbon-free side of the debate (though I always keep some around for things such as medication removal, etc.).

All that aside, if you want to continue using activated carbon, the lifespan is generally in the two week range before the carbon becomes "deactivated."

Pasfur 01-25-2010 06:54 AM


Originally Posted by MOA (Post 312313)

Carbon does not absorb all organics and it does not typically absorb those responsible for the creation of nitrate.

Sorry MOA, this statement is not accurate. Organics present themselves in 2 forms, with both polar and non-polar molecules. Each form of waste will eventually break down and be processed biologically. For the record, beneficial aerobic bacteria process this organic waste into Nitrate. By definition, the post contradicts itself.

From Martin Moe's, "Marine Aquarium Reference, Systems and Invertebrates", hard back page # 222:
"Activated carbon is the most common and cost effective media used for chemical filtration... Activated carbon absorbs the nonpolar, hydrophobic organic molecules from the system water... It is highly effective in removing the organic molecules... and also very effective in removing toxic organic compounds and heavy metals."

Moe does go on to state that different grades of carbon have different preferences for what molecules they will absorb, and that you should purchase carbon manufactured for use in an aquarium. Also, as iamntbatman points out, Moe reminds the reader to replace carbon frequently.

I understand this is a freshwater thread. I just grabbed the closest book I saw. The statement above is so inaccurate that I knew every reference on my shelf would provide the necessary material.

This really isn't a big deal. I just find that many FW fishkeepers avoid the use of activated carbon because they do not understand the benefits, yet almost all the reference material and experts in our field continue to this day to recommend and use activated carbon on their home systems. Again, with the exception of live plant tanks.

mrdemin 01-25-2010 08:39 AM

I use carbon, its such a pain to remove it from the filter pads that I use. However, I am halfway done to emptying the current pad and will be carbon free soon (maybe). I do have a few plants in my tank though, and I want to see if there will be any difference between using and not using carbon.
I have my tank up since around Oct, and have been running activated carbon since... I don't think anything will be different if I stop using it.

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