Originally Posted by MOA
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.