rfoote wrote: R+M/2

Smarta@@   

How long do you leave it in for?  Do you use it passive (in a sock in the sump) or active (in a canister with pumped water passing through)?

Let's talk about the petroleum industry again...

Ya, what the h*ll does an oil man know about water anyway?  Let's change the topic... Anyone know what the "R+M/2" octane rating on the gas pump means?

JF, I guess that I will need to check into this a bit. True, pores will fill with organisms as easily as contaminants. However, there is a bit more to it than that I would believe. Not being a chemist, biologist or micro organism...ist...guy... I cannot offer an educated answer right now. Realistically, backflushing is key to extending the life of media. If this is done (by hose or other means), I would personally believe that the media's life is being cut too short. Additionally, using a prefilter that is cleaned periodically will help, let's say filtering to 1 to 5 micron nominal. Pressurizing through the media also helps.

But hey, if it works for you... Personally, I leave mine in for A LOT longer than you do... so far so good. Wanna test my water?

Let's talk about the petroleum industry again...    

jfinch wrote: OCl-        +          C          =          CO2       +         Cl- chlorine          Activated              Carbon           Chloride Ion (as chlorate)    Carbon                Dioxide           (harmless)

  I seem to have messed up the equation (that's why I graduated in chemical engineering, not chemistry ).  Thanks Gonzo for seeing that!  I'm glad someone was actually looking at it...  It should be:

2 OCl-     +    C    =     CO2    +    2 Cl-

Yes, adsorbtion is the reason I use it.  Oh you were getting at the longitivity issue... we may dissagree here .  Here's a past thread where we talked about this:  http://www.utahreefs.com/forum/forum_posts.asp?TID=1006.  Here's a quote from my post explaining my belief:

I think that when using the same bag of carbon for more then a week it's just working as substrate for bacteria.  The average pore size (diameter) is much much smaller then a single bacteria.  Once bacteria are established on the carbon surface they act like a "cover" over the surface keeping organic molecules from permeating into the active sites.  Therefore, when I use carbon I use a small amount and change it every week and when I do a water change.

I assumed the comments above were more directed at culinary water where bacteria growth is not an issue.  If it weren't for the bacteria, I think carbon could last very long indeed.  Some people suggest pulling the carbon bag out of the sump every week and "smashing" it against the counter top to break it up a bit and expose new surfaces to extend it's life.  I'm problably in the minority when it comes to this...

(not Culligan Man... how 'bout Kinetico Man )

LOL... Thanks for the scientific input JF! I did know that GAC actually reacted to/with chlorine, but wanted to dig a bit into the myth that it was very short lived as filtrate. It is quite effective as a media and has significant longevity. Adsorbtion is probably it's largest role in filtration, I am sure that you would agree. I must say though, not thrilled with the Culligan Man reference.

Sean, what it means is that GAC is a good thing. It's truly beneficial to a filtration system, although maybe not necessary in many setups. Don't fear the carbon!