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.

 

[slice]

There are very few absolute answers in this hobby. As an engineer myself, I also wished for a magic formula when starting out.
Observation and experience is the key in my opinion.
I use carbon and change it about every 3 weeks or so, based on observation.

 

[bang guy]

I agree, there is not yet an absolute answer for this. I have confirmed for myself that it loses most of its effectiveness after 48 hours.
I typically only ran GAC a couple days a month to clear up gelbstoff. I always had a dry canister loaded with clean GAC ready to go in case of emergency.

 

[elrodg]

Ok here is my 2cents.
If you are using the fine granules of AC then yes they do lose their effectiveness rather quickly. But in my experience with using coarse grit to pellet sized carbon it seems to have a longer submerged life. Somewhere around two to three weeks. Granted you have to rinse it for hours.
But there is a definite answer as to their uses in a tank: The presence of dissolved organic matter (humic material in particular) in source water decreases the effectiveness of granular activated carbon filters in the treatment of water. Results from potentiometric titrations, electrophoretic mobility measurements and BET surface area analyses suggest that this may be due to an increase in the negative charge on the carbon surface and a decrease in available surface area after adsorption. An increase in pH and the application of heat causes organics to release. After a subsequent acid treatment the carbon exhibits an increased ability to adsorb dissolved organic material.
X-ray photoelectron spectroscopy was used to examine the carbon surface before adsorption, after adsorption and after regeneration treatment.
In laymans terms. Soak your carbon in vinegar then microwave or put it in the oven for a minute or two then rinse and reuse.
I did my research paper in college on this very topic lol.
Opportunity is often missed because its dressed in coveralls and looks like work

 

[elrodg]

If there is something that you are trying to pull out of your water then a carbon insert would certainly help.
In a freshwater setting this would apply for melafix, or an ich treatment. But to just act as an all time filter it's quite pointless.
I recommend using an aragonite insert, bio balls and/or floss. Pillow stuffing is a great alternative as well.
Opportunity is often missed because its dressed in coveralls and looks like work

 

[mhayes462]

If it only lasts 48 hrs, why do some have carbon reactors? What about using it to just polish the water and make it clear?
Mike Hayes

 

[acrylic51]

I think the effectiveness is longer than 48 hours.......As far as recharging/reusing, not really worth the trouble just replace it IMO.....

 

[snakeblitz33]

I run my carbon on a 60 day cycle for the most part. Never had any problems in almost 16 years of being an aquarist. I dont let technicalities get in the way of my experience.

 

[mhayes462]

I think my point has been made in this theard alone. We got answers from 48hrs to 60 days!! How has gotten so far apart? Is there a way to tell when your carbon has been depleted? Is that how people come up with their answers? If so, I'm missing it. I used to run chemipure elite in my old Biocube and I could tell I needed to change it when I'd have to clean my glass more often. I understand diferences in tanks make an impact, but 48hrs to 60 days? After soooo many yrs, how have aquarists not come closer in opinion. It seems like its just all up for speculation. Has there not been studies done?

 

[elrodg]

Every manufacturer of ac is different. All ac is not the same. Different surface areas, different absorption rates, and therefore you cannot say across the board that all carbon lasts x amount of time.
Opportunity is often missed because its dressed in coveralls and looks like work

 

[2quills]

Yep and you really have look at how the carbon is being used in the system as well. Carbon traps so much stuff. It can act much like mechanical filtration in a way that it's eventually going to get clogged up with organic and inorganic matter, which from what I understand is the main reason why the stuff doesn't last for a couple of years. Depending on how much of those things are in the water column in your system may render the carbon much less effective a lot sooner than it would in someone elses system. Is the water pre-filtered before it is ran through the carbon on your system? Look at the carbon blocks on R/O filter systems and how long are they rated for? When you really start digging into it I suspect that you'll find the answers that you seek really aren't as black and white as you might think.
I change mine roughly once a month and have done so for years not just on my saltwater tank but freshwater as well. Can't say that I've ever observed any major leaching, or HLLE in my tang and it's always kept my water crystal clear. I've stuck with API activated carbon cause it's cheap and easy to get a hold of. JME

 

[mhayes462]

Alright, I'm getting all that. Here's what I DON'T get and I haven't been able find an answer for. Is there a way to tell when it is depleted? How are they able to tell if its depleted after 48hrs? Are they guessing, assumptions, someone else told them that? Or is there really a way to know?
Mike Hayes

 

[bang guy]

Hi Mike, when I did my experiments I used a seperate smaller reef tank and replaced clear water with unclear from my main display tank. I tried several different frequencies of replacing the water and the results for me were always the same. It stopped clearing up the gelbstof after about 2 days.

 

[2quills]

Quote:
Originally Posted by mhayes462 http:///t/393433/much-debated-topic-any-absolute-answers#post_3500577
Alright, I'm getting all that. Here's what I DON'T get and I haven't been able find an answer for. Is there a way to tell when it is depleted? How are they able to tell if its depleted after 48hrs? Are they guessing, assumptions, someone else told them that? Or is there really a way to know?
Mike Hayes
Perhaps you can look into what it is that the carbon removes, or better yet find the specific reasons why you are using it and what you want it to remove and purchase some lab grade test kits to determine how effective it is in your system and for how long. Site and smell can give you some clues but I don't think that that's going to tell you the hole story. Or maybe you can call the manufacturers and ask them some questions. I just did a quick search and found numerous test results with charts that have been performed in these regards, not so much for the hobby, but more for drinking water.

 

[bang guy]

Most of these results are from fresh water testing. I think this is why there might be so much debate on this. The carbon block for an RO system seems to work fine for 6 months or so.

 

[2quills]

Agree, surely there arent as much organics floating around in our drinking water as there are in our system which is why I dont wait 6 months to replace. For me replacing once a month works fine. Though im sure its not doing much of anything after a week or two in my canisters.

 

[elrodg]

Well the only real way to tell is by an x ray photoelectric spectroscope. That allows you to measure the tiny holes in the granules and over a period of (x) days the holes will become clogged and virtually disappear.
Opportunity is often missed because its dressed in coveralls and looks like work

 

[elrodg]

Actually canisters have the best rate of depletion because it requires larger ac
And bang. Water is water regardless of what's in it. A saline environment would actually cause the ac to do the exact same thing. And at relatively the same rate.
My entire college career was spent studying water conservation for what it's worth
Opportunity is often missed because its dressed in coveralls and looks like work