Carbon

[jonathan.]

2 weeks is again a generalization. The manufacturer of most carbon will suggest 4-6 weeks in a "typical" reef environment based on whatever amount they prescribe. I'm not saying to trust this duration but it is probably the safe amount based on a couple of factors:

1) They have conducted their own study as to the effectiveness of their product in a variety of setups.
2) They are in the business of having you consume the product as fast as possible so you will buy more so their stated duration will probably be less than the true life of the product.

GAC's purpose is to remove inorganics. If you are dosing heavily on products like Iodine, Copper, Strontium, etc. then obviously, the life of the product will be shortened. I don't know where you get this 2 weeks notion from. I'm not saying you're wrong, but there is no data to support your case.

As for the notion of leeching back, this happens only if the carbon is fully saturated. It will selectively "leech" back the least adsorptive compound for something that it has greater affinity for.

I would say not only for a reef tank but for a freshwater system. In my experience working with the tanks at the job, we put a few huge carbon bags (I usually keep 2-3 depending on how many I can fit) under each 300G set-up. They are toast within about a week. These are bags rated for 200G systems as well. And the FW tanks don't get dosed with anything outside of being fed every other day.

The salt water display tank is around the same for the most part.

Now, granted, these systems are holding hundreds of fish per system, but I think it's a good example of the short lifespan of activated carbon.

 

[calaxa]

Jonathan,

I think your work system is atypical. The bioload is much higher than most reefers. You guys are probably erring on side of caution which is good. Carbon is cheap anyway especially in the bulk amount you guys probably buy. I do agree that GAC has a short lifespan for an aquarium setting and I also would toss it sooner rather than later. Wasn't trying to stir anything up with you.......I was just trying to defend Jim's point regarding your 2 week statement.

 

[jonathan.]

Jonathan,

I think your work system is atypical. The bioload is much higher than most reefers. You guys are probably erring on side of caution which is good. Carbon is cheap anyway especially in the bulk amount you guys probably buy. I do agree that GAC has a short lifespan for an aquarium setting and I also would toss it sooner rather than later. Wasn't trying to stir anything up with you.......I was just trying to defend Jim's point regarding your 2 week statement.

No, I didn't take it as you trying to stir something up. I was just providing another example.

I'm of the camp that thinks the general/average rule is only 2 weeks but that there are many, many exceptions (such as my work system for example).

 

[qwik]

I think waiting for your water color to change (slight yellow) is already to late . I would think at that point you are past its absorption abilities . Maybe seeing how long it takes to do it the first time and then using this as a timetable might be better . This is just my opinion,I know others with degrees feel different but to each his own . Changing it out a little too soon will not be all that more expensive considering the value of what is in your system !