Is Carbon, Nitrate, and Phosphate Dosing Bad For the Hobby?

[Mortie31]

I don't think anyone would argue that you can't oversize a skimmer but I do think that some system are best served with a larger skimmer not because of the Bioload but because of the sudden changes in Bioload. The only thing that will stop a skimmer from being able to remove DOCs is if there are not enough proteins for the skimmer to form a proper foam head. In this case if two skimmers have the same neck diameter but one has a larger reaction chamber and more air input the larger skimmer is undoubtedly better. I also believe that the amount of waste required to form a foam head on most hobbyist sized skimmers is not as significant as people believe it to be as a foam head immediately forms after even light feeding. Because of this going with a larger skimmer with a neck diameter only 20% bigger will not result in any significant performance loss but will serve as a buffer against larger and sudden nutrient inflows.

This is where I get confused as your claim and Ikes is in direct conflict to the 3 Feldman experiments, and I can’t find anything on searches to show me that he is wrong, I’ve been on the chemistry forum and searched as advised and can’t find anything. What experiment or discussion have you followed to come to your conclusion? A link would be ideal. Thanks Paul

 

[Mortie31]

This extract below is taken from this paper https://www.advancedaquarist.com/2010/1/aafeature
This to me says that only 20-35% of TOC is hydophobic and can be skimmed, and therefore the rest cannot no matter how good or big your skimmer is! The rate of removal is not discussed but once it’s gone it’s gone and 65%+ is still left.

One of the more surprising and important observations to emerge from the earlier skimmer studies was that the four original skimmers tested removed only 20 - 30% of the measurable TOC in the reef tank water examined; the remaining 70 - 80% of the TOC was not removed by skimming. Extension of these measurements to the three new skimmers tested in this study did not add much to the argument. The Reef Octopus' removal amount fell within this range, whereas the Bubble King and Royal Exclusiv skimmers appeared to remove incrementally more of the extant TOC, perhaps up to the mid-30% range. An explanation for this observation was offered in the January 2009 Advanced Aquarist article; in summary, skimmers can only remove what bubbles trap, and bubbles only trap molecules and/or particles (i.e., bacteria, diatoms, etc.) with some compelling thermodynamic reason to adhere to the bubble's surface. On the molecular level, this surface association is typically driven by the molecule/particle having a hydrophobic (= water hating) patch that can be buried in the bubble surface/interior. This arrangement avoids the energetically penalizing juxtaposition of hydrophobic surfaces with (hydrophilic) water, and so overall the system energy is lowered (a favorable occurrence). Some of the molecules/particles in aquarium water will meet this hydrophobic region criterion, and some will not. The ones that do not have a sufficiently large hydrophobic patch will not interact with bubbles, and hence will not be removed by skimming. From, the results of the experiments described here, it appears that only 20 - 35 % of the measurable TOC meets this hydrophobicity criterion (= [TOCl] defined earlier) whereas the remaining 65 - 80 % does not (= [TOCr] defined earlier). In essence, bubbles are a rather poor media for removal of organic nutrients from aquarium water compared to, for example, GAC. However, they do have the distinct benefit of being cheap.

 

[Montiman]

This extract below is taken from this paper https://www.advancedaquarist.com/2010/1/aafeature
This to me says that only 20-35% of TOC is hydophobic and can be skimmed, and therefore the rest cannot no matter how good or big your skimmer is! The rate of removal is not discussed but once it’s gone it’s gone and 65%+ is still left.

One of the more surprising and important observations to emerge from the earlier skimmer studies was that the four original skimmers tested removed only 20 - 30% of the measurable TOC in the reef tank water examined; the remaining 70 - 80% of the TOC was not removed by skimming. Extension of these measurements to the three new skimmers tested in this study did not add much to the argument. The Reef Octopus' removal amount fell within this range, whereas the Bubble King and Royal Exclusiv skimmers appeared to remove incrementally more of the extant TOC, perhaps up to the mid-30% range. An explanation for this observation was offered in the January 2009 Advanced Aquarist article; in summary, skimmers can only remove what bubbles trap, and bubbles only trap molecules and/or particles (i.e., bacteria, diatoms, etc.) with some compelling thermodynamic reason to adhere to the bubble's surface. On the molecular level, this surface association is typically driven by the molecule/particle having a hydrophobic (= water hating) patch that can be buried in the bubble surface/interior. This arrangement avoids the energetically penalizing juxtaposition of hydrophobic surfaces with (hydrophilic) water, and so overall the system energy is lowered (a favorable occurrence). Some of the molecules/particles in aquarium water will meet this hydrophobic region criterion, and some will not. The ones that do not have a sufficiently large hydrophobic patch will not interact with bubbles, and hence will not be removed by skimming. From, the results of the experiments described here, it appears that only 20 - 35 % of the measurable TOC meets this hydrophobicity criterion (= [TOCl] defined earlier) whereas the remaining 65 - 80 % does not (= [TOCr] defined earlier). In essence, bubbles are a rather poor media for removal of organic nutrients from aquarium water compared to, for example, GAC. However, they do have the distinct benefit of being cheap.

I am very familiar with the study you quote and I find it one of the most compelling articles concerning how we choose a skimmer. I would not claim that a larger skimmer could remove more TOC than a smaller skimmer. So why don't we use 2 in diameter skimmers on every tank?

I believe it comes down to 2 main reasons.
1. Larger skimmers can remove large amounts of DOCs faster
2.Small skimmers will clog with skimmate faster limiting performance quicker.

My argument when sizing a skimmer is to size the skimmer based on the largest amount of organics you anticipate entering the system . If you have a holding system where livestock move in and out constantly and the bioload is high because of corals slimming up and some livestock losses. I would size my skimmer according to the peak load. If you periodically do broadcast feedings of amino acids and coral foods the skimmer should be sized based on this. If you are worried about a large anemone getting sucked into the power head your skimmer should be sized based on this.

Over all I do not believe that a larger skimmer will make the tank cleaner but rather respond faster and keep going longer in the event of a sudden nutrient spike. If a large clam dies while I am out of town I will be greatfull for the over sized skimmer. I also do not see any significant down side to going larger as the only performance detractor I could see is that some small amount of organics will stay in the system longer because there is not enough organics to form the foam head.

I can not quote an article on this but I will say having spoken to many engineers working for multiple skimmer manufactures they all agree to these points.

1. A smaller neck will form a foam head at a lower level of organics than a larger neck.
2. A smaller neck will clog faster than a larger neck
3. A larger neck will allow a faster rate of skimmate collection in comparison to a smaller neck.

This is all that my conclusions are based off of and challenging it would require questioning these assumptions, or perhaps the magnitude of their effects.

 

[Mortie31]

I am very familiar with the study you quote and I find it one of the most compelling articles concerning how we choose a skimmer. I would not claim that a larger skimmer could remove more TOC than a smaller skimmer. So why don't we use 2 in diameter skimmers on every tank?

I believe it comes down to 2 main reasons.
1. Larger skimmers can remove large amounts of DOCs faster
2.Small skimmers will clog with skimmate faster limiting performance quicker.

My argument when sizing a skimmer is to size the skimmer based on the largest amount of organics you anticipate entering the system . If you have a holding system where livestock move in and out constantly and the bioload is high because of corals slimming up and some livestock losses. I would size my skimmer according to the peak load. If you periodically do broadcast feedings of amino acids and coral foods the skimmer should be sized based on this. If you are worried about a large anemone getting sucked into the power head your skimmer should be sized based on this.

Over all I do not believe that a larger skimmer will make the tank cleaner but rather respond faster and keep going longer in the event of a sudden nutrient spike. If a large clam dies while I am out of town I will be greatfull for the over sized skimmer. I also do not see any significant down side to going larger as the only performance detractor I could see is that some small amount of organics will stay in the system longer because there is not enough organics to form the foam head.

I can not quote an article on this but I will say having spoken to many engineers working for multiple skimmer manufactures they all agree to these points.

1. A smaller neck will form a foam head at a lower level of organics than a larger neck.
2. A smaller neck will clog faster than a larger neck
3. A larger neck will allow a faster rate of skimmate collection in comparison to a smaller neck.

This is all that my conclusions are based off of and challenging it would require questioning these assumptions, or perhaps the magnitude of their effects.

Thanks for writing this, your conclusions about skimmer neck volume was one Feldman also arrived at, that bigger removed faster.

 

[Mortie31]

I am very familiar with the study you quote and I find it one of the most compelling articles concerning how we choose a skimmer. I would not claim that a larger skimmer could remove more TOC than a smaller skimmer. So why don't we use 2 in diameter skimmers on every tank?

I believe it comes down to 2 main reasons.
1. Larger skimmers can remove large amounts of DOCs faster
2.Small skimmers will clog with skimmate faster limiting performance quicker.

My argument when sizing a skimmer is to size the skimmer based on the largest amount of organics you anticipate entering the system . If you have a holding system where livestock move in and out constantly and the bioload is high because of corals slimming up and some livestock losses. I would size my skimmer according to the peak load. If you periodically do broadcast feedings of amino acids and coral foods the skimmer should be sized based on this. If you are worried about a large anemone getting sucked into the power head your skimmer should be sized based on this.

Over all I do not believe that a larger skimmer will make the tank cleaner but rather respond faster and keep going longer in the event of a sudden nutrient spike. If a large clam dies while I am out of town I will be greatfull for the over sized skimmer. I also do not see any significant down side to going larger as the only performance detractor I could see is that some small amount of organics will stay in the system longer because there is not enough organics to form the foam head.

I can not quote an article on this but I will say having spoken to many engineers working for multiple skimmer manufactures they all agree to these points.

1. A smaller neck will form a foam head at a lower level of organics than a larger neck.
2. A smaller neck will clog faster than a larger neck
3. A larger neck will allow a faster rate of skimmate collection in comparison to a smaller neck.

This is all that my conclusions are based off of and challenging it would require questioning these assumptions, or perhaps the magnitude of their effects.

What are your opinions on the 65%+ TOC that isn’t hydrophilic? And how to remove it, do you run GAC in a filter at all? Or rely on bacteria to control?

 

[Montiman]

What are your opinions on the 65%+ TOC that isn’t hydrophilic? And how to remove it, do you run GAC in a filter at all? Or rely on bacteria to control?

I personally don't use GAC all the time but I do periodically. I do use ozone which helps simplify these compounds if not remove them. I also believe both bacteria based and algae based filters can remove the remaining TOC effectively.

 

[Ike]

I personally don't use GAC all the time but I do periodically. I do use ozone which helps simplify these compounds if not remove them. I also believe both bacteria based and algae based filters can remove the remaining TOC effectively.

I think GAC used sparingly once a month for a few days is a great way to polish the water but it’s mainly remove yellowing compounds and probably has little impact on TOC.

 

[Dana Riddle]

It would be easy to spike a sterol sample with organic carbon and 'filter' with GAC, PolyFilter, etc. and look at BOD5. Just time consuming.

 

[Mortie31]

I think GAC used sparingly once a month for a few days is a great way to polish the water but it’s mainly remove yellowing compounds and probably has little impact on TOC.

GAC is a effective at removing TOC from our tanks... unless Feldman is wrong.. and indeed GAC can be used statically as a systems main filter. A Hiatt filter system

Hiatt filtration system.

Has anyone here tried the HIATT FILTRATION SYSTEM. From all the hype it looks incredible but I was wondering has anyone tried this. It is basically TRBC (special carbon) Right now bacteria. then there are add ons like ph rock etc. I am in no way selling this stuff I am just wondering ...

www.reef2reef.com

Feldmans summation..

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration

What are the bacteria populations in the water column of reef tanks, and how does that value compare with bacterial counts in authentic reef water? Does carbon dosing indeed increase water column bacteria populations (i.e., is growth carbon limited)? Does mechanical filtration (protein skimming...

www.advancedaquarist.com

1. Reef aquaria utilizing active filtration (GAC, skimming) maintain equilibrium TOC levels within the range found on healthy tropical reefs.
2. Protein skimming (i.e., bubbles) is not very effective at removing TOC from aquarium water, depleting typical reef tank water of only ~ 20 - 35% of the post-feeding TOC present.
3. GAC filtration is quite effective at stripping reef tank water of its TOC load, removing 60 - 85% of the TOC present.
4. And, quite intriguingly, the natural biological filtration, which starts with bacteria and other microbes, is remarkable in its capacity to remediate reef tank water of TOC, easily removing 50% or more of the post-feeding TOC increase in tank water.

 

[Mortie31]

GAC is a effective at removing TOC from our tanks... unless Feldman is wrong.. and indeed GAC can be used statically as a systems main filter. A Hiatt filter system

Hiatt filtration system.

Has anyone here tried the HIATT FILTRATION SYSTEM. From all the hype it looks incredible but I was wondering has anyone tried this. It is basically TRBC (special carbon) Right now bacteria. then there are add ons like ph rock etc. I am in no way selling this stuff I am just wondering ...

www.reef2reef.com

Feldmans summation..

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration

What are the bacteria populations in the water column of reef tanks, and how does that value compare with bacterial counts in authentic reef water? Does carbon dosing indeed increase water column bacteria populations (i.e., is growth carbon limited)? Does mechanical filtration (protein skimming...

www.advancedaquarist.com

1. Reef aquaria utilizing active filtration (GAC, skimming) maintain equilibrium TOC levels within the range found on healthy tropical reefs.
2. Protein skimming (i.e., bubbles) is not very effective at removing TOC from aquarium water, depleting typical reef tank water of only ~ 20 - 35% of the post-feeding TOC present.
3. GAC filtration is quite effective at stripping reef tank water of its TOC load, removing 60 - 85% of the TOC present.
4. And, quite intriguingly, the natural biological filtration, which starts with bacteria and other microbes, is remarkable in its capacity to remediate reef tank water of TOC, easily removing 50% or more of the post-feeding TOC increase in tank water.

Didn’t you set a Hiatt filter up recently @Jomama ?

 

[Dr. Dendrostein]

Didn’t you set a Hiatt filter up recently @Jomama ?

I did, it does what they say. Every three days you dose a sugar base liquid called unstuck. Just have to follow instructions to the tee. Only drawback is availability, not many places to buy.

 

[Ike]

GAC is a effective at removing TOC from our tanks... unless Feldman is wrong.. and indeed GAC can be used statically as a systems main filter. A Hiatt filter system

Hiatt filtration system.

Has anyone here tried the HIATT FILTRATION SYSTEM. From all the hype it looks incredible but I was wondering has anyone tried this. It is basically TRBC (special carbon) Right now bacteria. then there are add ons like ph rock etc. I am in no way selling this stuff I am just wondering ...

www.reef2reef.com

Feldmans summation..

Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration

What are the bacteria populations in the water column of reef tanks, and how does that value compare with bacterial counts in authentic reef water? Does carbon dosing indeed increase water column bacteria populations (i.e., is growth carbon limited)? Does mechanical filtration (protein skimming...

www.advancedaquarist.com

1. Reef aquaria utilizing active filtration (GAC, skimming) maintain equilibrium TOC levels within the range found on healthy tropical reefs.
2. Protein skimming (i.e., bubbles) is not very effective at removing TOC from aquarium water, depleting typical reef tank water of only ~ 20 - 35% of the post-feeding TOC present.
3. GAC filtration is quite effective at stripping reef tank water of its TOC load, removing 60 - 85% of the TOC present.
4. And, quite intriguingly, the natural biological filtration, which starts with bacteria and other microbes, is remarkable in its capacity to remediate reef tank water of TOC, easily removing 50% or more of the post-feeding TOC increase in tank water.

Interesting, I'm shocked that it's removing that much ToC. If that's true it seems like GAC would be exausted almost immediately upon being added to our tanks if it's used in a somewhat typical amount. I need to make the time to read over the article...

 

[Mortie31]

Interesting, I'm shocked that it's removing that much ToC. If that's true it seems like GAC would be exausted almost immediately upon being added to our tanks if it's used in a somewhat typical amount. I need to make the time to read over the article...

Well yes it is used up very quickly depending on the level of organics, it’s an incredibly porous, sponge in essence, and if you think about how quickly it can clear yellowing of tank water, which is in the main just removing excess organics from the water. I’ve wondered if it’s this quick removal of organics which has led to perceived issues with it, is it lowering levels to much? Zeovit systems recommend using GAC passively 24/7 and to shake the bag regularly, I’m starting to wonder if this GAC is really behind very low nutrient levels and perhaps as much as the zeo rocks themselves..

 

[Ike]

This is where I get confused as your claim and Ikes is in direct conflict to the 3 Feldman experiments, and I can’t find anything on searches to show me that he is wrong, I’ve been on the chemistry forum and searched as advised and can’t find anything. What experiment or discussion have you followed to come to your conclusion? A link would be ideal. Thanks Paul

I've been doing this for a long time, I've had dozens of protein skimmers and many systems. Common sense and observation in that time simply doesn't jive with there being a percentage cap to what can be skimmed, and small skimmers being able to perform as well as large ones. The simple notion that processing more water and faster will remove compounds that it can remove (ammonia and various DOC) faster, and before they break down into things that can't be skimmed out like nitrite, nitrate, phosphate. Could it be all the difference between a great and a good tank with elevated nutrients?

Consider being just a few percentage points lower on speed and effectiveness for removal. One system maintains nitrate at low levels, detecteable, at say .5 ppm, the other builds up excess as small as .3 ppm daily excess of nitrate that it can't process because water is not being processed quite as well or as quickly... Someone smarter than me can do the math, but the TOC percentage difference between those two scenarios could be as little as a fraction of a percent. It doesn't take much at all to make that difference, now add that up over years and tell me if a bigger and slightly more efficient skimmer is worth it.

 

[Mortie31]

I've been doing this for a long time, I've had dozens of protein skimmers and many systems. Common sense and observation in that time simply doesn't jive with there being a percentage cap to what can be skimmed, and small skimmers being able to perform as well as large ones. The simple notion that processing more water and faster will remove compounds that it can remove (ammonia and various DOC) faster, and before they break down into things that can't be skimmed out like nitrite, nitrate, phosphate. Could it be all the difference between a great and a good tank with elevated nutrients?

Consider being just a few percentage points lower on speed and effectiveness for removal. One system maintains nitrate at low levels, detecteable, at say .5 ppm, the other builds up excess as small as .3 ppm daily excess of nitrate that it can't process because water is not being processed quite as well or as quickly... Someone smarter than me can do the math, but the TOC percentage difference between those two scenarios could be as little as a fraction of a percent. It doesn't take much at all to make that difference, now add that up over years and tell me if a bigger and slightly more efficient skimmer is worth it.

Ike a lot of us have been doing this a long time, (there’s no need to be patronising) you have obviously had considerable success with your tank, that is undeniable, I do agree small diferences can and generally do make or break success. However where we differ is I’m looking for the science behind why we get the results we get and your going by your experience. As long as we personally end up with the system we want it doesn’t matter which approach we personally take. It’s upto others which route they choose but I will always point out the science especially when it contradicts what someone is offering as advice based on experience that can be read by everyone from beginners to seasoned veterans, it’s always good to debate these things. I don’t know if Feldmans findings are 100% correct or not, as no one can offer any proof or even rudimentary measurements to the contrary I’m going to stick to his findings. As this discussion is on DOC, as I pointed out in a previous post that you haven’t got back to me on yet, is that GAC is more effective than skimming at removing DOC’s and the natural bacterial processes in our tanks just as good.. so potentially by encouraging more beneficial bacteria that may be better than over sized skimmers...

 

[Mortie31]

@Ike As a skimmer can only skim hydrophilic DOC, I guess the important question as to how much DOC a skimmer can remove is; what percentage of DOC is hydrophilic?
From a paper studying NOM (natural organic matter) in the Mediterranean

https://pdfs.semanticscholar.org/3757/085e70db462d3f1035de3fd638cd86441b42.pdf

This is a passage from the conclusions
“Natural organic matter has been defined as mainly hydrophilic (70%) and slightly transphilic (24%). Hydrophobic compounds have a high SUVA254 (almost 5) characteristic of humic substances. From LC-OCD results, seawater appears mainly composed of humics and LMW neutrals (37 and 40% of DOC, respectively). The LMW neutrals are hydrophilic whereas humics contains hydrophobic, transphilic and hydrophilic that shows the advanced hydrolysis of humics in seawater that would explain the more hydrophilic nature of natural organic matter from seawater.”
So my take on this is 70% of Med water is mainly hydrophilic and this is made up of humics and LWM, humics are not totally hydrophilic so 37% may not be totally skimmable, so even If a skimmer could remove 100% of hydrophilic DOC they will only be removing about 50% of of the NOM..
This isn’t a study of tank water, so nothing conclusive, but hints at the potential limits and may partly explain why bacteria and GAC uptake more DOC as there not hydrophilic limited.

 

[Graffiti Spot]

I think it’s about time for someone to do a new skimmer study.
I always use a very large oversized skimmer and as long as the neck size is appropriate for the bioload and skimmer size then I have never had any of my skimmers “sit idle with nothing to skim”. I also think a carbon source is a huge plus in this matter. Using one has always helped keep my skimmer running and producing very good skim. I also agree that there is a lot more a skimmer provides and takes out than just organic carbon.

 

[Mark Gray]

I voted Yes I had to remove all my Cheato to get my NO3 and PO$ up now they are a little high but it's not a problem

 

[jda]

I have no links, but Dr. Holmes-Farley, in the past, has had a lot of disagreement with the Feldman study and assessment. Something about the testing method of the TOC in the skim mate vs. actual removal of organics is non sequitur. I forget all of the details, but he was strongly advising people not to believe that only 20-35% is accurate and that over time, a skimmer could get much, much more.

It might be worth the time to search his forum for this. It was very compelling and also matches up moreso with the bulk of hobbyist experiences.

I too keep multiple skimmers on my tanks (at least two in each) and have seen nothing but wonderful results. On one tank, I have a RO with the sicce PSK (their best skimmer ever, IMO) which pulls nasty junk. I also have a LifeReef which also pulls tons of nasty junk. If either goes offline, the other just does what it does - no more, no less. It is like the other one is not even there.

Also, keep in mind that once GAC get coated in organics, that it does not act like GAC anymore since the water can penetrate it.

 

[Mortie31]

I have no links, but Dr. Holmes-Farley, in the past, has had a lot of disagreement with the Feldman study and assessment. Something about the testing method of the TOC in the skim mate vs. actual removal of organics is non sequitur. I forget all of the details, but he was strongly advising people not to believe that only 20-35% is accurate and that over time, a skimmer could get much, much more.

It might be worth the time to search his forum for this. It was very compelling and also matches up moreso with the bulk of hobbyist experiences.

I too keep multiple skimmers on my tanks (at least two in each) and have seen nothing but wonderful results. On one tank, I have a RO with the sicce PSK (their best skimmer ever, IMO) which pulls nasty junk. I also have a LifeReef which also pulls tons of nasty junk. If either goes offline, the other just does what it does - no more, no less. It is like the other one is not even there.

Also, keep in mind that once GAC get coated in organics, that it does not act like GAC anymore since the water can penetrate it.

I did research RHF and the chemistry forum, and sadly couldn’t find anything, I actually asked for a link on post #161, unfortunately no one posted one. Even if feldman was 100% in error it’s still only 50- 60%
Don’t get me wrong I think a skimmer is valuable and I’d never run a tank without a properly sized one, I’m just trying to get to the bottom of do they actually remove as much as some people claim and is a systems success just down to this. Regarding GAC yes unless it’s shaken up it will quickly coat up, which is potentially why Zeo recommend this to be done daily... did you look at the Hiatt filter and method I posted earlier? It’s only by discussing that we move forward and maybe start to tease out what actually is working, how and the benefits and look for ways to improve..