What's the difference between all these carbons...really!?!?!

[RussC]

So really, is it that much different between all the different carbons? I see where BRS offers Bituminous, Lignite, and ROX with claims ROX is the best on the market and only uses 1 tablespoon for every 10 gallons. Then I go to my LFS and they tell me Matrix Carbon can't be beat. Most efficient. And then they mentioned something I was not aware of. All carbons contain phosphate. Different carbons have different levels. I must have missed that class. I was aware of carbon having PH impact. But is it really that much of an impact? And what kind of phosphates are we talking about? What is the real difference when you get down to the bottom line....really?!?!

 

[Scrubber_steve]

you want to select a carbon known for having a pore structure similar in size to the molecules your trying to remove. “


“For instance; carbon made from bituminous coal has a network full of very small pores.”

“Carbon produced from lignite has a very large average pore size. If we were trying to remove a small molecule like chlorine bituminous would be a good choice.
However, in the actual aquarium where trying remove much larger organic compounds and color pigments, so the larger pore network found in lignite carbon will perform much better.”

ROX 0.8 is the best

 

[AlSimmons]

How long does it last? When does that GAC just become a media bag? (biological filter)

 

[Bpb]

You're maybe wanting a specific answer to a question that is one that we really cannot answer. The best answer you can hope for you just got. Different carbons = different pore sizes at a molecular level. They remove different types of compounds from the water. Yes. There is a difference.

Bituminous and lignite are natural products. Rox is manmade. It lasts longer and has a more complex pore structure containing a wide array of pore sizes. It is also harder with far less dust.


Literally nobody can truly give you a cutoff time on when carbon goes from effective to just being biomedia. It will gradually lose its effectiveness over time as the reactive surfaces get filled with carbon bonds. There's no real way to measure that. Dirtier tanks will use it up faster. Larger amounts will last longer. That's about as specific as anyone can reasonably get. Most people replace their carbon every 2-4 weeks


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[AlSimmons]

Kind of like the bubbles in a BTA, no?

 

[Scrubber_steve]

How long does it last? When does that GAC just become a media bag? (biological filter)

Some people check the color of their tank water in a white bucket to guage the condition of the carbon. If the water is yellow the carbon is spent as the yellowing organics should be easily removed.
Using the recommended amount of carbon, & changing it on a regular basis keeps the level of DOC at low levels.
If you don't do regular water changes a larger volume of carbon is recommended.