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Activated carbon

Tinajo

AC Members
I use an AquaClear filter in my tank. It comes with a sponge, activated carbon, and something that looks like white pellets (I can’t recall their name). I know not to change the sponge because that’s where the bacteria is, but what about the carbon? I think the box says to change it monthly, but could it go longer?
 

authmal

Pseudonovice
Not really. Carbon adsorbs (not absorbs) impurities. If it's full and left in the tank, it will leach those same impurities back into the water. Purigen takes much longer to reach that stage. Besides, most people don't really need to use carbon in most instances. The best use is to remove medications from the water after treatment.
 

FreshyFresh

Global Moderator
Staff member
Carbon or other chemical media is not needed in your tank unless you have a water clarity issue or you want to remove meds, etc. I would skip it if those don't apply to you.

In my aquaclear filters, I just run the sponge block and bag of bio media. You are correct in that some beneficial bacteria lives in the sponge, but it also lives on/in the ceramic pellets. That mesh bag is marketed as being your bio media for this filter. You can add more of that if you want or add more sponge.
 

Rbishop

...and over the edge.
Staff member
Adsorb of impurities is a chemical bond with activated carbon. It can't and won't leach back onto the tank. Fact. Not unless the temp is taken to about 4700F to break that bond.
 

FreshyFresh

Global Moderator
Staff member
I think a more likely phenomena people refer to with carbon 'leaching back' has more to do with the carbon being left in the filter so long, it's loaded with solids and starting to crumble to the point once you disturb it, all that loveliness can wind up in the tank.
 

Rbishop

...and over the edge.
Staff member
True...a definite sign of improved mechanical filtration required with possible more frequent cleaning.
 
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fishorama

AC Members
Yeah, I agree with both FF & Bob, there only so much "stuff" carbon can adsorb. After that, it becomes, like all tank surfaces, a place for beneficial bacteria to grow. Beyond that, it just traps debris that can spew back into the tank causing a mess of brown yuck all over the place (like diatoms but worse!!). This is another reason to clean filters regularly; sponges & ceramic "bio-bits" can do this too if not rinsed fairly often.

I never use carbon unless I'm trying to remove meds...along with lots of water changes. But I keep all the carbon packets or pads in case I need them. I have a lots & lots stashed over the years, lol.
 
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