Carbon - What exactly does it Take Out of the Water? (Both Good and Bad)

[gammon186]

In regards to GAC affecting iron in its ferric state. Does this mean that all GFO's phosphate removers are negated by the use of carbon?

 

[Randy Holmes-Farley]

In regards to GAC affecting iron in its ferric state. Does this mean that all GFO's phosphate removers are negated by the use of carbon?

No.

In GFO, the phosphate is binding to the exposed iron oxide surface of a solid particle. Such particles won't bind to GAC, and GAC won't impact them.

FWIW, there is almost no free ferric iron in seawater. It is highly insoluble. Almost all iron in seawater, whether ferric or ferrous, will be bound to organics. These organics may bind to GAC, but it is unrelated to GFO usage.

 

[gammon186]

Thanks for clearing that up!

 

[Mstanker]

So the basic answer to the question was?

 

[Dr.Reefgood]

I use carbon pretty much 24/7 in small amounts. Less than a Tablespoon for every 10gal. I like the look of crystal clear water, and during the times i have run out or let it run too long i can notice the yellow tinge. I have been advised to use a high end GAC because lesser quality has been known to leach phosphates. I have also been told that if you skim regularly there should be no need for carbon. Also that carbon absorbs trace elements. Though i have never read anything or ran a test to show anything substantial is lost. I also do small water change once a week. So i use carbon for a chemical filtration i guess. You can drink pond water if you run it thru enough charcoal. Sounds like a good water cleaner to me. Never seen any negative effects, though i have heard of the Head and Lateral line disease. I am having some issues with some zoa's in an LPS tank that has been running carbon for 8 months. But is it the GAC's fault???

 

[Randy Holmes-Farley]

So the basic answer to the question was?

Which question?

 

[enrique]

What is the most eficient flow for a GAC reactor?

 

[that Reef Guy]

I use carbon pretty much 24/7 in small amounts. Less than a Tablespoon for every 10gal. I like the look of crystal clear water, and during the times i have run out or let it run too long i can notice the yellow tinge. I have been advised to use a high end GAC because lesser quality has been known to leach phosphates. I have also been told that if you skim regularly there should be no need for carbon. Also that carbon absorbs trace elements. Though i have never read anything or ran a test to show anything substantial is lost. I also do small water change once a week. So i use carbon for a chemical filtration i guess. You can drink pond water if you run it thru enough charcoal. Sounds like a good water cleaner to me. Never seen any negative effects, though i have heard of the Head and Lateral line disease. I am having some issues with some zoa's in an LPS tank that has been running carbon for 8 months. But is it the GAC's fault???

Wait so Carbon will take out Phosphate?

 

[Randy Holmes-Farley]

Wait so Carbon will take out Phosphate?

No, but it removes organics before those organics are able to break down and potentially release phosphate.

FWIW, that effect is relatively small compared to a binder like GFO.

Some people are concerned about phosphate that comes attached to some brands of fresh GAC from the manufacturing process. I've written about this and I think it is not something to be concerned with as the amount present is much smaller than in a single feeding.

 

[enrique]

Randy, what is a most efficient flow rate for a GAC reactor? thanks

 

[3Twinklets]

I use GAC 24/7 also. It has had no affect on my Zoas.

I'm interested in the effect on zoanthids.

 

[Randy Holmes-Farley]

Randy, what is a most efficient flow rate for a GAC reactor? thanks

I don't specifically know the answer to that question, but here's my thought on it:

1. You don't want to break apart the GAC, so flow so high it gets pulverized wouldn't be good.

2. Up to the point where the flow becomes so high that pockets of open space (gas) appear (which may be higher than anyone really uses), higher flow seems better for two reasons.

First, bringing dirty water to the GAC faster rather than leaving it "sitting" in partially cleaned water from some exposure to GAC already would seem desirable.

Second, faster flow reduces the thin unstirred water layer on the surface of particles. Molecules are slow to diffuse through this layer, so making it thinner would be desirable.

3. You don't want flow so high that it strips molecules off of the surface, but I don't know if we can attain such high flow rates in any normal reef application.

So overall I think medium flow or higher is good. Not slow flow, which would be best in a single pass application (like an RO/DI carbon block), but not in a recirculating application as we use it.

I know there is at least one experiment floating around that claims to show that ramping up flow made GAC bind less effectively. I'm not convinced by it. Maybe not better binding as flow increased, but not reduced (IMO).

 

[marke]

Is it true if the flow is high it will cause tumbling which will release gac powder into our display? And if so what can we use to remove that?

 

[Randy Holmes-Farley]

I expect that it could, but some types are more resistant than others.

In any case, I wouldn't want to tumble GAC too much.

I use it in a canister filter, mixed with GFO.

I think if you get GAC bits in the water, skimming will help remove it, but I'm not sure what else might.

 

[swk]

I use GAC in my tank 24/7 and my Zoas are doing very well.

I hear of many people using the ROX carbon. However, I see that it is double the price of the lignite carbon which I'm currently using. Why is ROX considered to be so much better of a product?

 

[Randy Holmes-Farley]

It is acid washed (less likely to release bits and impurities) and, I think, it may be stronger and have a higher surface area than many types of GAC.

Here's a data sheet on it:

http://www.norit.com/files/documents/ROX08_rev8.pdf

 

[stlcard]

so whats our favorite brands of Carbon?

Im about to try BRS Rox. Ive been using Fluval, interested to see if the rox does improve as much as people say.

 

[CastAway]

I'm pretty new, six months into my first tank, about 210g total volume. I made what I've only now come to know was a mistake. Just over a month ago I started using GAC. I had three mesh bags with Velcro tops, and put 16oz's of GAC in one bag, rinsed it, and put it in my sump in a compartment where it would see a lot of flow. Seven days later I started the second 16oz bag, and seven days after that the third. May plan was to cycle the bags, replacing the GAC in each after a month or so of use. A few days after I changed out the first bag, a fellow reefer let me know that what I did may have shocked some SPS I had (three birds nests lost) and that it was way way too much. Thing is, if indeed it was the culprit, I only lost the birds nest. All my zoas and everything else seems fine. I had attributed by SPS loss to an alk swing, but, now I suspect the GAC.

So, how much is too much? What does too much do? What does it remove that is so beneficial to corals? Or, is it just the "sudden" change that's problematic?

 

[coralcruze]

I'm going to throw this out there... I don't condone this practice if you are just starting out. I do it because I've been in the hobby 16 years and have found alternate methods to keeping my tank clean... so here goes. I hardly ever use carbon... I've stoped using it for over 5 years. My tank hasnt been better since. Not this isnt to say that I never use it. I still think carbon is great if yu need to get meds out of the water or something accidentally dropped in and you want to me on the safe side. I also don't use GFO.

I have switched to using bio pellet reactor which seems to work but i also implement refugium with macro growth, mangroves and a tight well defined and automated feeding schedule. I think there are benefits to carbon but not for running everyday 24/7 unless you are just starting out in the hobby and making mistakes is a more common occurance.

side note: Randy, I'm glad to find you here as you have been instrumental throughout the years in helping me through many chem. problems and issues. Thank you sir!

 

[coralcruze]

so whats our favorite brands of Carbon?

Im about to try BRS Rox. Ive been using Fluval, interested to see if the rox does improve as much as people say.

IMHO stay away from BRS Rox. way too efficient. No need for that kind of efficiency and its also more costly. Fluval is fine, really...