carbon - when to change?

[ryanpal]

hey all.

i was recently introduced to carbon a few months ago. i've put a few "sacks" of carbon in my sump. my question is, when should these be replaced?

thanks,
ryan

[LobsterOfJustice]

There have been a few polls and most people replace monthly. However, I have heard that carbon's ability to absorb water-discoloring compounds (as opposed to other compounds and chemicals) lasts anywhere from a few days to only a few hours.

I would try to find a more efficient way of running your carbon. A sack sitting passively in the sump is not pushing water through the carbon, and you are not getting the most out of it. I would be surprised if it is doing much of anything, honestly. I would reccomend running carbon in a power filter, canister filter, or fluidized reactor (i.e. phosban reactor). Or if you have a filter sock on your drain, you can put a bag of carbon in there.