Need Some Help Here

[raptorrex]

i've been searching for information on Carbon. it is a commonly held truth that carbon can, when full, release toxins back into the tank!

however try as i might i can find no mention of this, in my searches anyway, can anybody help? it may well be that the information is there but my chemistry is just not up to understanding it. i could really do with some help on this.

 

[tmack]

I've often wondered myself if this was really true or not. I don't have time to spend much time surfing (I'm at work), but I did find this site:

http/www.hallman.org/filter/gac.html

Based on the comment in here, it looks unlikely (or at least rarely) that the used carbon would release the toxics that it had adsorbed:

"Activated carbon removes organic compounds from aquaria by adsorption and absorption principles. Both processes involve the transfer of the adsorbate (pollutant) from the liquid phase (water) to the solid phase (carbon). Adsorption is the primary sorption mode relying on electrostatic Van der Walls forces. This attractive “forceâ€￾ forms relatively weak bonds between the carbon and adsorbate. In theory activated carbon could release or desorb what it removed at some point. But practical experience with aquarium filtration and laboratory experiments show desorption rarely occurs or causes any type of “toxic releaseâ€￾. Bacteria readily colonize the outer surface of the activated carbon and consume some of the sorbed organics. The bacterial action reactivates a small portion of the carbon and perhaps prevents desorption. "

Hope that helps.

 

[raptorrex]

thanks tmack!

looks like we have a commonly held misconception here! and it may well be an important one.

that is unless anyone else knows better!

 

[tmack]

You're welcome boboboy. It's just one site, but at least it was a scientific study under aquarium conditions. It may go against the usual "commonly held truths", but I always look for hard evidence and facts rather than opionions or heresay. I found it interesting.

 

[raptorrex]

it comes up whenever Carbon is mentioned! has nobody any proof that deadsorbtion, is even possible in an aquarium?