Much debated topic. Any absolute answers?

[Mhayes462]

The topic is running gac, or carbon. I have yet to find any clear answers on running it. Lots of people have they're own opinions and thoughts on it. As in how long to run it before it needs changed? How long does it stay effective? Does it leach after a certain time? Some say run it for a day or so and pull it, some say a month is good before it needs changed. Hell, some say only run it when you're trying to take care of a problem! So which is it?! I'm a very absolute thinker, black and white. I hate confusion. After all these years has nobody been able to come up with absolute answers on this subject? If not, why? Lets hear it. Maybe we can get some clear answers.


Mike Hayes

[disc1]

Unfortunately you're not going to get a clear cut black and white answer. There are a number of factors that go into it and no two tanks are identical. What works in one may not be best for another.

[Mhayes462]

That shouldn't change the carbon though. Granted, in some tanks it may have more to absorb and therefore need changed sooner. But what about running it continuously on a well maintained reef tank with no problems. Even then, some say its not effective to run it continuously.


Mike Hayes

[reefgeezer]

Hi Mike. You're asking for a black & white answer that doesn't exist. If you were to ask "how often do you use GAC, how often do you change it, and why?" then there could be some answers that were more objective.

I'll start... I run a small amount (about three heaping tablespoons) in a reactor and change it every two weeks. I have a couple of leathers in my tank and wish to have some GAC to filter whatever they might release. I also like the polishing effect it has and think it removes organics that my skimmer doesn't. .

[Tank Girl]

I use about two cups on 130 gal system and change it every two weeks.

[swcc]

I think that for the most part after two weeks the carbon tends to be more of a surface area for bacteria vs adsorption media, so change it in two week intervals. The problem with carbon is there is no way to know with certainty the point where it stops providing benefit and needs to be changed(thus people are all over the board on their amounts used and change schedule). One could use purigen instead, and at least this way you know when it is dirty it needs to be recharged/replaced. Interesting enough, purigen works tremendous compared to GAC in our freshwater tank. I run an UV so I do not use any media in my reef system.