Activated carbon research-Pro's and Con's

[flamehawk]

MOst on this board have said that carbon should be used minimaly and only passively as oppose to all the time. I've just read 2 articles in FAMA (1-'02) which seem to contradict this. Julian Sprung writes on page 56 that A good brand of activated carbon will keep the water sparkiling and remove many dissolved organis compounds....It also serves as a biological filtration function after it has been in the aquarium FOR MORE THAN ONE MONTH....This statement seems to support the notion that ac s/b kept on all the time and for a longer period than this board has generally suggested.
In the same edition starting on pg 160 there is a scientific research article which among other things states...Usually good quality ac remains active for a period of about 6 months. After that replace about 30% of it and at the same time wash the rst of it with aquarium water. Again contrary to allot of what has been said. This article in particular has allott of credibility since all of it seems to be abcked up with controlled experiments.
Would lik eto here from all of you on these findings. Thanks.

 

[up north hermit]

OK.......I'll go first.
"a good brand of carbon"........well, please elaborate on what is good. Is it research grade?
"Also serves as a biological filtration function" is exactly why most reefers DO NOT want this to occur in their reef tanks, creating more nitrate to fuel more unwanted algaes in their display tanks. And to the notion that this doesn't occur until the carbon has been in the tank for one month I think is underestimated. When all the pores are filled or coated with organics and a bacterical slime, the carbon is deactivated and then functions ONLY as a biological filter---but this DEPENDS ON BACTERICAL LOAD.
Generalized statements such as Sprung expounds without reference to the particulars of the "controlled experiments", can lead to much confusion. In fact, carbon and its use, will vary widely from system to system. Systems with high biological loads, no protein skimming, no tricke filter, and little algae growth would benefit (obviously) from more extensive carbon filtration than the more balanced, well-filtered (i.e, algae turf scrubbers, refrugiums,skimmers, etc) systems (which is the current trend).
Bottom line is that there are many variables, and no two systems are alike. Each aquarist must decide for him or herself which is the appropriate course of filtration is best for their personal eco-system.
As always, I'm a moderate.

I just take that middle of the road route. A little carbon a few days a month, changed and rinsed often.
One thing is undebate-able: if you choose to run cabon 24/7 in your reef, you need to pay extra attention to trace element addition.
My humble .02, as always
Hermit

 

[flamehawk]

Hermit,
Thanks for the response.
I'm really surprised others haven't jumped on this one. Anyone else??

 

[garyfla]

Hi
Okay here's my .02 cents The use of
carbos is STILL a hotly debated issue
in FW and any other system that uses them
First they vary a lot what they're made of
how they are manufactured and how they're
packaged.How could you compare them?
One thing for sure they absorb all sorts of things but tell me how long will this last
Eventually it will become unbalanced and everything will be released.I would think that as soon as bacterial activity begins
you would see a downward spiral of the absorbtion capibilities.Again varying by type,bioload,the aquatic solution.
In marine aquaria the ideal is a lot of
trace elements.Some of these have been proven to be essential and carbon will absorb them all. There is no free lunch
evryone would have to weigh the ads.vs dis.
IME carbons are either too good or worthless.
Gary

 

[flamehawk]

I sent e-mails to two marine biologists who also have over 60 years of saltwater fishkeeping experience and also to Julian Sprung, renowned author and known epxert on reef set-ups. Some may not like what they have to say about carbon but I feel compelled to share so that all can make their own judgement:
Sprung writes...The amount of time that AC is effective at keeping the water clear varies depending on the production of water-staining organic material in the tank, and the amount used. It also varies with the type of carbon. In general most carbons are "spent" after about THREE TO FOUR months usage. Six months is possible, and it's certainly fine to leave the carbon in there as long as you wish- IT DOES NOT BECOME A NITRATE FACTORY...on the contrary, AC typically develops populations of facultative anaerobes that denitrify the water.
The reason why some aquarists recommend changing only 1/3 at a time is because they don't want to lose this biological denitrafying capacity.
It's really up to you whether you want to use carbon intermittently or continuously. I RECOMMEND CONTINUOUS usage for reef tanks to keep the water consistently colorless. If you allow the water to yellow and then use carbon, the change in color allows more light penetration(esp. UV wavelengths) and may cause corals to bleach. ( end of Julian Sprung feedback).
Summary of other two marine biologist: Most types of AC are good for up to 4-6 weeks. Afetr the carbon has lost it's absorbtion ability it will become a bio filter bed. This would be good on it's own and would not contribute to nitrate buildup, however the carbon has already adsorbed a lot of organic material before bacteria becoming a bio filter bed. As this begins to be fed on by the bacteria NITRATES WILL INCREASE RAPIDLY. Carbon is used continuously and changed once a month, not entirely but most of it is changed at the same time.
What to do????
My conclusion: I will keep using act.carbon continuously in my tanks and change it at least once every 4 weeks. Most of it but not all. Hope this helps.

 

[flamehawk]

Anyone else care to comment about this latest opinion on Acticvated Carbon. They also had something to say about DSB's and I'm not sure user's are going to like it either but again I'll post it for people's info in the reef tank section.

 

[nitrex]

Over the past three years I had to manage my 75 from a distance. During that time I kept only two fish in the tank, a flame angel and a tomato clown. So the bio load for a 75 was extremely low, plus the tank had already been running for 5yrs before that. But during that three yr period I never once changed the activated carbon b/c all my test were extremely low, particluarily the nitrates (Don't fix what's not broken, a hard thing in the SWF hobby). I never performed a water change, only added well water to top it off. Whether or not the carbon played a role in helping keep nitrates down is still up for debate, but you'd think that even w/a minimal bio load over three yrs. the nitrates would still accumulate. BTW, I was using reserach grade carbon if anyone is wondering.
Also, my tank doesn't use LR or LS, only a wet/dry. I also only had enough aragonite to just barely cover the bottom..the point is I am not sure where else the nitrate could have been absorbed?
Who knows?

 

[garyfla]

Hi
How about carrying the idea a step further
and use AC rather than a DSB?IME any AC
is eventually very biologically active no doubt about that
Say in a sump or refugia?You could change
part of it or leave it alone could also be mixed with other materials With tests you could get a fair idea of what it is doing
IME nitrates were far more of a problem than buffering What do you think
Gary

 

[flamehawk]

I'm re-posting this since not many actually viewed the original. While I would love to here from everyone, at least read it and store it in the knowledge banks. Good hobbying!!