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Old 01/02/2018, 07:40 PM   #26
bertoni
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Quote:
Originally Posted by Belgian Anthias View Post
Of coarse all bacteria may grow when given enough ammonia and other building materials but when the usable organic carbon is matched the heterotrops will use up most of the ammonia leaving very little or nothing for the nitrifiers and other organisms because of the very high grow rate. This is supported by all approved publications I have read about ammonia reduction in aquaculture systems .
That's probably true, but I don't see the relevance.
Quote:
Which are the standard microbes? Nitrifiers and denitrifiers?
How one can avoid the bacteria to overlap "physically"?
By inhabiting difference parts of the live rock, or by growing in the water column, as beginning examples. Denitrification has been posited to happen more in pores than on lit surfaces, for example. Heterotrophic consumption might be less restricted (or not).

Quote:
For me It is logic that when ammonia is removed by assimilation this ammonia is not available for nitrification and denitrification. It is a fact that autotrophs are suppressed by heterotroph growth.
Again, likely true, but irrelevant to this discussion.


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Old 01/03/2018, 02:02 AM   #27
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Originally Posted by bertoni View Post
I'm not sure why this matters. The end result is the consumption of nitrate, and I think we've all seen that dosing requires per-tank tuning.
If it does not matter?!
The end result is possibly a tank that may have no nitrification capacity at all. A full active and populated tank with the same nitrification and denitrification capacity as a new tank may be the result. Is the possibility that this situation may be created insignificant or neglect able ? For me this problem is a decision maker and solving it a priority before I would take the risk for dosing carbohydrates.
My opinion the doses should be based in function of the C:N ratio . But how this can be done?
How can one "fine tune" carbon dosing based on the nitrate concentration without taking the risk bringing the tank in a dangerous situation and this to "fine tune" something that is no threat and certainly not dangerous for the tank at all.?


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/03/2018, 03:10 AM   #28
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Originally Posted by bertoni View Post
That's probably true, but I don't see the relevance.

By inhabiting difference parts of the live rock, or by growing in the water column, as beginning examples. Denitrification has been posited to happen more in pores than on lit surfaces, for example. Heterotrophic consumption might be less restricted (or not).


Again, likely true, but irrelevant to this discussion.
No relevance to this discussion?
This discussion is about assimilative ammonia and assimilative nitrate reduction and about the ammonia reduction rate which makes out the carrying capacity of each system. Nitrate by itself is not a concern at all in this discussion.

The carrying capacity and the calculation of the max bioload is explained in a publication of Spotte, S., 1979. Fish and invertebrate culture: water management in closed systems, 2d ed. ed. Wiley, New York. This is relevant lecture ! Basics for managing an aquarium.


How denitrifiers can install when there is no or little nitrate produced due to maintaining a high C:N ratio.?
Nitrate is a key factor for a healthy biofilm as it is used for recycling the biomass within any biofilm for oxidizing the produced HS. http://www.baharini.eu/baharini/doku...of_the_biofilm
Assimilative heterotrophs grow on the surface of a biofilm and in the water column and will influence the biological balance all over the system as they are the main oxygen and building material consumers due to the very high growth rate. Carbon dosing effects all organisms directly or indirectly.
Carbon dosing will prevent the construction of balanced mixotrophe biofilms.
Live rock is a biofilter with a low capacity, certainly when high a C/N ratio is maintained as the pores will clog. Anyway, if a high C:N ratio is maintained the function of live rock and other biofilters is bypassed as no or little nitrate will be produced.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)

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Old 01/03/2018, 04:28 AM   #29
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Originally Posted by Dan_P View Post
How do I register? What’s the Dutch word I am looking to click to register?
Maybe you could cut and paste the references into this post so we can at least read the science behind conjectures.


On the Dutch page "Toegang geweigerd" below the login button you will find the Dutch word "Registreren"

When you use this link: http://www.baharini.eu/baharin/doku....iwitafschuimer the access denied page is not shown as this page is made public for the moment. In the left side upper corner of the page you find a login button to register in English

When a link is used containig id=en: for example http://www.baharini.eu/baharini/doku...chemie:biofilm the access denied page is in English.

Once registered you will receive a login in your mailbox

We have to do it this way to protect the rights of the authors as most references used are consult able for private use only and the content may not be published without respecting the publishing rights on the article or paper. If content of the wiki is used for publication on the web one must refer to the article with a link to the page in question. Content of consult able references may only be used for publication with the permission of the authors or/and publisher of the publication.

In the left upper corner of each wiki page one can switch languages.

it is possible to use the wiki for your own articles.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)

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Old 01/03/2018, 05:04 AM   #30
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Originally Posted by DiscusHeckel View Post
You have not answered my previous question about the use of activated carbon to harvest the produced biomass.
It will certainly help reducing TOC and DOC.
In fact better as a skimmer as it is known that a skimmer removes max 35% of TOC. Not skim able TOC will stay behind and build up, skim able TOC is removed. Bacteria are forced to use not skim able DOC.
The use off skimmers is in discussion because of the selective way they feed and remove live bacteria and the effect on the bacterial balance and evolution on the long term in a closed environment. It would be interesting to know which strains are skimmed and which strains are not skimmed. Which strains are favoured by not skim able DOC. In fact, most live bacteria removed are not skimmed but carried out on the foam. http://www.baharini.eu/baharini/doku...iwitafschuimer.
The use of skimmers is an other discussion.

Activated carbon will not prevent that the produced protein due to carbon dosing will be consumed and become part of the food chain. As far as I know it does not absorb life bacteria ( with the exception of those which grow on it the moment it is removed).


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)

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Old 01/03/2018, 05:50 AM   #31
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Originally Posted by bertoni View Post
I

A lot of things can be skimmed, and characterizing what comes out of the skimmer back into what was in the tank would be non-trivial, in my opinion. One guess is that carbon dosing removes nutrients by feeding bacteria that release skimmable organics. It's also likely that at least some of the carbon is consumed by bacteria that are themselves skimmed, but I don't know how much that would be.
This has been part of a research project of the University of Pennsylvania by Ken S. Feldman, Kelly M. Maers. Department of Chemistry, The Pennsylvania State University, University Park, PA 16802.
So no complete guess work any more as we have results. The organics removed are included in the 35% which was determined to be the maximum TOC removed by a skimmer. They concluded that concerning skimmers there is more difference in price as there is difference in the ability to remove TOC and DOC. Skimmers are very selective in removing live bacteria, some strains are removed, some are not. Most are not skimmed but carried out on the foam. http://www.baharini.eu/baharini/doku...iwitafschuimer


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/03/2018, 11:50 AM   #32
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Originally Posted by Belgian Anthias View Post
On the Dutch page "Toegang geweigerd" below the login button you will find the Dutch word "Registreren"

When you use this link: http://www.baharini.eu/baharin/doku....iwitafschuimer the access denied page is not shown as this page is made public for the moment. In the left side upper corner of the page you find a login button to register in English

When a link is used containig id=en: for example http://www.baharini.eu/baharini/doku...chemie:biofilm the access denied page is in English.

Once registered you will receive a login in your mailbox

We have to do it this way to protect the rights of the authors as most references used are consult able for private use only and the content may not be published without respecting the publishing rights on the article or paper. If content of the wiki is used for publication on the web one must refer to the article with a link to the page in question. Content of consult able references may only be used for publication with the permission of the authors or/and publisher of the publication.

In the left upper corner of each wiki page one can switch languages.

it is possible to use the wiki for your own articles.

I am in! Thanks very much! Connecting with information and ideas is the reason I find this site so useful and interesting.

Everyone else on this thread might want to register and read the information first hand. Enough is in English to get some useful information.


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Old 01/03/2018, 02:25 PM   #33
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If it does not matter?!
The end result is possibly a tank that may have no nitrification capacity at all. A full active and populated tank with the same nitrification and denitrification capacity as a new tank may be the result. Is the possibility that this situation may be created insignificant or neglect able ? For me this problem is a decision maker and solving it a priority before I would take the risk for dosing carbohydrates.
My opinion the doses should be based in function of the C:N ratio . But how this can be done?
How can one "fine tune" carbon dosing based on the nitrate concentration without taking the risk bringing the tank in a dangerous situation and this to "fine tune" something that is no threat and certainly not dangerous for the tank at all.?
I don't understand what you are saying here. As long as the nitrate level is acceptable, whether the level is maintained by denitrification or by carbon dosing seems irrelevant. Tuning the dose (the carbon input) to match the nitrate imported via food requires some trial and error, but doesn't seem to be a significant problem.


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Old 01/03/2018, 02:53 PM   #34
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Originally Posted by Belgian Anthias View Post
No relevance to this discussion?
This discussion is about assimilative ammonia and assimilative nitrate reduction and about the ammonia reduction rate which makes out the carrying capacity of each system. Nitrate by itself is not a concern at all in this discussion.

The carrying capacity and the calculation of the max bioload is explained in a publication of Spotte, S., 1979. Fish and invertebrate culture: water management in closed systems, 2d ed. ed. Wiley, New York. This is relevant lecture ! Basics for managing an aquarium.


How denitrifiers can install when there is no or little nitrate produced due to maintaining a high C:N ratio.?
Nitrate is a key factor for a healthy biofilm as it is used for recycling the biomass within any biofilm for oxidizing the produced HS. http://www.baharini.eu/baharini/doku...of_the_biofilm
Assimilative heterotrophs grow on the surface of a biofilm and in the water column and will influence the biological balance all over the system as they are the main oxygen and building material consumers due to the very high growth rate. Carbon dosing effects all organisms directly or indirectly.
Carbon dosing will prevent the construction of balanced mixotrophe biofilms.
Live rock is a biofilter with a low capacity, certainly when high a C/N ratio is maintained as the pores will clog. Anyway, if a high C:N ratio is maintained the function of live rock and other biofilters is bypassed as no or little nitrate will be produced.
I don't see the relevance of this information. Whether nitrate is produced or not doesn't seem relevant to me. As long as the basic parameters are acceptable, the fish and corals should be fine.


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Old 01/03/2018, 02:54 PM   #35
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This has been part of a research project of the University of Pennsylvania by Ken S. Feldman, Kelly M. Maers. Department of Chemistry, The Pennsylvania State University, University Park, PA 16802.
So no complete guess work any more as we have results. The organics removed are included in the 35% which was determined to be the maximum TOC removed by a skimmer. They concluded that concerning skimmers there is more difference in price as there is difference in the ability to remove TOC and DOC. Skimmers are very selective in removing live bacteria, some strains are removed, some are not. Most are not skimmed but carried out on the foam. http://www.baharini.eu/baharini/doku...iwitafschuimer
You've posted that paper before. I still don't understand the relevance. What are you trying to say?


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Old 01/03/2018, 05:18 PM   #36
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1) ďAll this implements a very low nitrification and denitrification capacity.Ē

2) ďAn aquarium system that is kept in balance by carbohydrate dosing has a limited carrying capacity. Such systems are vulnerable for a system crash due to the well known new tank syndrome.Ē

3) ďOnce started dosing it may be difficult to stopĒ

I think the above three statements are the key proposals or conjectures concerning carbon dosing.

I have wondered to what extent carbon dosing diminishes our normal or assumed normal nitrification-denitrification system. I think a genomic survey during the start up of carbon dosing would need to be conducted to look for the population shift in bacterial species to address this hypothesis. The literature I have come across would seem to suggest that one could expect an impact on the nitrification-denitrification system.

The second conjecture is of a quantitative nature which I assume refers to a systemís ammonia removal capability, or is it the nitrate removal capability? The claim of an increase risk of a system crash is new to me. Also, system crash is a hobby term that is loosely defined. New tank syndrome, or bad beginnerís luck, is also too broadly used. But if system crash and new tank syndrome refers to high ammonia concentration, then I would ask where is the data of carbon dosing causing ammonia spikes. Anyway, the proposal needs clarification.

Finally, the third proposal might be derivative of the aphorism ďnever change or do anything quickly to an aquariumĒ. Has anyone suddenly stopped dosing carbon and observed what happens? Maybe not.

Good discussion so far.

Dan


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Old 01/03/2018, 05:43 PM   #37
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If my memory is correct, a number of people have reported stopping carbon dosing without tapering off, but I might be mistaken. If I get some time, I'll try to search some.


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Old 01/03/2018, 06:11 PM   #38
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Would this be why KZ/Zeovit requires zeolite ammonia adsorbant & carbon. Also why they add nitrate to their carbon source have anything to do with it all?


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Old 01/03/2018, 07:27 PM   #39
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I think the zeolite acts as artificial live rock or a bacterial substrate of some sort over the long term. It won't adsorb ammonia indefinitely unless the ammonia is consumed in some way.

Adding nitrate to the carbon source would allow the product to remove phosphate from the water column after fixed nitrogen has become limiting. Maybe their guess is that most tanks will be nitrogen-limited before enough phosphate has been removed.


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Old 01/04/2018, 03:24 AM   #40
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Respiratory Nar system

A lot of heterotrops and autotrophs ( denitrifiers) have also or only a transport system for nitrate take up for respiration. This respiratory Nar system is triggered by nitrate, suppressed by oxygen and is not sensitive for ammonia. http://www.baharini.eu/baharini/doku...traat_reductie

In most normal biofilms surrounded by oxygen saturated seawater denitrification takes place. Oxygen is consumed in the outer layers of the film in a way not enough oxygen can reach the middle and lower zones . In normal circumstances, about 1/3 of the oxygen is used by heterotrops and 2/3 for nitrification, +- 1/3 of the ammonia is reduced by heterotrops and +-2/3 by autotrops.
An oxygen minimum zone ( OMZ) is created within the film, ideal for autotrophe denitrification. The Nar system of autotrop denitrifiers may be triggered at an oxygen level above 0,5 ppm. Autotroph denitrification is limited because of the limited availability of usable sulphur provided by HS production within the film. This limited autotrop denitrification is necessary for recycling HS formed due to decay within the film, back to sulphur or sulphate. In the sub layers anoxic conditions may be created and heterotroph denitrification may be activated. Most heterotrophs need an oxygen level lower as 0,5 ppm to trigger the Nar system. The heterotroph denitrification is limited by the available organic carbon provided by normal decay within the biofilm and the limited anoxic space. http://www.baharini.eu/baharini/doku...chemie:biofilm

When a high C:N ratio is maintained by carbohydrate dosing most ammonia is assimilated in the water column but also in the biofilm. The structure of the biofilm will change drastically as the nitrifiers are overgrown by the very fast growing heterotrops and lose the battle for oxygen. As the nitrifiers are suppressed the ammonia they normally use is available for assimilation. Due to the very high growth and oxygen consumption in and on the outer layers of the film the OMZ zone may become anoxic making more heterotroph denitrification possible. When not enough nitrate is available, sulphate will be used.
After some time the biodilm will become mostly heterotropic due to the competition for nitrate in the low oxygen zone and the high decay rate providing organics. HS will not be recycled any more within the biofilm but oxidised when leaving the biofilm producing sulphate.
Autotrophs are outcompeted! The autotrophic ammonia reduction potential which was build up is lost.

An other biologic balance will be found and the heterotroph growth may be matched to keep this balance by maintaining a balancing C:N ratio. This means regular and continues dosing.

More nitrate may be removed effectively from the system by increased heterotroph denitrification.

Keeping a low slightly increased C:N ratio may induce a higher mixotroph denitrification rate within a normal nitrifying biofilm. This can also be done by providing some more usable sulphur to the biofilm , this way eliminating daily matched dosing. http://www.baharini.eu/baharini/doku...ter#spc_system

For a biofilm in a very low oxygen environment ( live rock, DSB) this scenario may be a bit different. HS can not be oxidised when leaving the biofilm, may build up and be released as H2S gas.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/04/2018, 04:57 AM   #41
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The way it is done is irrelevant?

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Originally Posted by bertoni View Post
I don't understand what you are saying here. As long as the nitrate level is acceptable, whether the level is maintained by denitrification or by carbon dosing seems irrelevant. Tuning the dose (the carbon input) to match the nitrate imported via food requires some trial and error, but doesn't seem to be a significant problem.
The way it is done is irrelevant?

When nitrate is denitrified NO3-N is removed from the system and the carrying capacity, the ability of the system to remove ammonia, of the system is maintained at all times even when denitrification is interrupted or stopped for a period of time.

When nitrate must be assimilated first all NH4-N must be assimilated into biomass, than NO3-N may be used. As there is insufficient ammonia availability for nitrification no or little nitrate is produced and the nitrifying capacity is drastically reduced or stopped. The carrying capacity of the system, the ability to remove ammonia, may depend largely or completely on dosing. When dosing is interrupted or stopped the system needs time to reinstall sufficient autotrophic carrying capacity bringing the system in an unbalanced and possible very dangerous situation.
Most nitrogen is not removed but taken into a not ending cycle within the closed environment of the aquarium.

Leaves the other pro's and con's of both complete different applications.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/04/2018, 05:40 AM   #42
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Skimmer

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You've posted that paper before. I still don't understand the relevance. What are you trying to say?
As a lot of users think that a skimmer removes the biomass produced by carbon dosing the limited ability to remove biomass by skimmers is more than relevant.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/04/2018, 05:50 AM   #43
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"What to do with the continually increasing biomass " is one of the problems to solve.

If one is able to complete the food chain one can introduce some Litopenaeus vannamei,in a refuge which will be harvested when big enough to be consumed. This way nothing is lost.


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Current Tank Info: BBS: BADES Biofilm System. An aqua-system in wich the nitrogen cycle is closed by removing the daily nitrate production daily, every day, by incorporation of BADES (Biological Anaerobe Denitrification using Elemental Sulphur.)
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Old 01/04/2018, 02:20 PM   #44
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The way it is done is irrelevant?
That's my opinion.
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When dosing is interrupted or stopped the system needs time to reinstall sufficient autotrophic carrying capacity bringing the system in an unbalanced and possible very dangerous situation.
The system might or might not require much time to recover an ammonia-processing capacity. I don't see why this is relevant. If you're worried, just back off slowly on carbon dosing. That's what I generally recommend.

I'm not sure what you mean by "unbalanced". Balanced with respect to what? I also disagree about carbon dosing being particularly dangerous. I haven't seen any evidence of that since the dosing guidelines were created.


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Old 01/04/2018, 02:22 PM   #45
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As a lot of users think that a skimmer removes the biomass produced by carbon dosing the limited ability to remove biomass by skimmers is more than relevant.
The paper covers the effectiveness of skimming in one set of circumstances. I am not sure how this situation applies directly to carbon dosing.
Quote:
"What to do with the continually increasing biomass " is one of the problems to solve.
I see no evidence of a continually increasing biomass due to carbon dosing, nor do I understand how that could happen.


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Old 01/04/2018, 07:27 PM   #46
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I see no evidence of a continually increasing biomass due to carbon dosing, nor do I understand how that could happen.
I think the notion is that the carbon being dosed induces a growing number of bacteria. To assimilate nitrogen and phosphorous, bacterial biomass must increase. If the number of bacteria arenít increasing, the uptake of nitrogen and phosphorous will not be as high. I donít have a feeling for how long a bacterium that isnít dividing exists and if it does ďjustĒ live, how much material it needs to just hang around.

Where things get really fuzzy for me in this discussion is the rate of biomass accumulation in an aquarium, say for every gram of food you add to the tank. First, a lot of carbon is consumed for energy needs with CO2 given off. More than 50% I believe. What isnít eaten by the fish is consumed by bacteria, protozoa, fungus, etc. When bacterial biomass is eaten, more than half that carbon goes to CO2. When whatever ate the bacterium is eaten, half of that carbon goes to CO2. Carbon, and biomass, leave the aquarium as you move up the food chain. Do we know at what point that it accumulates at an unhealthy level? Is that point different for every system?

Nitrogen added to the aquarium by food either goes to either biomass or waste (N2, NH3, NO3, slowly metabolized organic nitrogen compounds). Changing the ratio of C:N in the food or by carbon dosing means shifting wasted nitrogen to biomass nitrogen. But at what point does this biomass derived from food need to be harvested. I suppose if bacterial biomass grows quicker than predation reduces it, you grow a visible slime. Or if the nitrogen level becomes too low to support a large population of bacteria that was created by carbon dosing, I guess the bacterial population declines or crashes, maybe releasing waste back into the aquarium. In either case, you would have needed to harvest bacterial biomass more aggressively. Still trying to wrap my head around what you would need to know to calculate this. I need to review the notion of bioload and see how other life forms are considered in estimating bioload limits.

Enjoying the insights.

Dan


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Old 01/04/2018, 08:04 PM   #47
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I think the notion is that the carbon being dosed induces a growing number of bacteria. To assimilate nitrogen and phosphorous, bacterial biomass must increase. If the number of bacteria aren’t increasing, the uptake of nitrogen and phosphorous will not be as high. I don’t have a feeling for how long a bacterium that isn’t dividing exists and if it does “just” live, how much material it needs to just hang around.
I agree that creating more net biomass is likely to consume nitrogen and phosphorus at a higher rate than other consumption patterns. That said, a lower consumption rate might be fine. Whether a tank takes an hour to consume a daily dose of vinegar or 12 hours, either way, nitrogen and phosphorus seem to be converted to a skimmable form in some tanks, from what we can see. The biomass must stop increasing at some point, or the tank would be filled (literally) with bacteria, but that does not imply that export stops, or won't be effective. For all we know, dying bacteria or their remains might be highly skimmable.

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Where things get really fuzzy for me in this discussion is the rate of biomass accumulation in an aquarium, say for every gram of food you add to the tank. First, a lot of carbon is consumed for energy needs with CO2 given off. More than 50% I believe. What isn’t eaten by the fish is consumed by bacteria, protozoa, fungus, etc. When bacterial biomass is eaten, more than half that carbon goes to CO2. When whatever ate the bacterium is eaten, half of that carbon goes to CO2. Carbon, and biomass, leave the aquarium as you move up the food chain. Do we know at what point that it accumulates at an unhealthy level? Is that point different for every system?
I certainly agree that we don't know much about the rate of biomass increase in our tanks. As far as bad effects of carbon dosing, in some cases, tanks seem to suffer from bacterial slimes or even cloudy water. I don't know whether those cases truly are dangerous, or just esthetic, but I tend towards caution when giving recommendations.

Of course, some bacteria might produce problematic or even toxic compounds. In addition, increasing the total organic load in the tank might cause problems. Some tanks might have issues of this type, which is why I tend to encourage a slow increase in the carbon dose. Even so, most problems seem to be starving corals, rather than organics. We lack useful tools to be sure what's happening, though. The same issue can occur in tanks without carbon dosing, as well.

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Nitrogen added to the aquarium by food either goes to either biomass or waste (N2, NH3, NO3, slowly metabolized organic nitrogen compounds). Changing the ratio of C:N in the food or by carbon dosing means shifting wasted nitrogen to biomass nitrogen. But at what point does this biomass derived from food need to be harvested.
"Harvesting" is a bit ambiguous here. If you mean direct harvesting by the person or persons running the tank, I doubt that there's any need to do so unless the owner prefers, for example, to run with a growing slime mass and siphoning it from the system. I haven't seen any signs that active harvesting is required. I agree that some set of organisms or viruses are consuming at least some or even most of the bacteria, but I don't know how to quantify that. Direct skimming might remove some bacteria directly, for example.

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I suppose if bacterial biomass grows quicker than predation reduces it, you grow a visible slime. Or if the nitrogen level becomes too low to support a large population of bacteria that was created by carbon dosing, I guess the bacterial population declines or crashes, maybe releasing waste back into the aquarium. In either case, you would have needed to harvest bacterial biomass more aggressively. Still trying to wrap my head around what you would need to know to calculate this. I need to review the notion of bioload and see how other life forms are considered in estimating bioload limits.
I agree that a visible slime is one possibility. I'm not so sure that bacterial crashes are going to be a significant danger. Bacterial populations can increase quite rapidly, generally, so I'd expect that a crash would be undetectable with hobbyist equipment. Stopping feeding seldom seems to cause issues, for example, and it's actually a step that I often recommend when dealing with various nutrient buildup or tank crash situations.


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Old 01/04/2018, 08:42 PM   #48
Dan_P
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I agree that creating more net biomass is likely to consume nitrogen and phosphorus at a higher rate than other consumption patterns. That said, a lower consumption rate might be fine. Whether a tank takes an hour to consume a daily dose of vinegar or 12 hours, either way, nitrogen and phosphorus seem to be converted to a skimmable form in some tanks, from what we can see. The biomass must stop increasing at some point, or the tank would be filled (literally) with bacteria, but that does not imply that export stops, or won't be effective. For all we know, dying bacteria or their remains might be highly skimmable.
Isnít the notion of carbon dosing essentially growing bacteria? And if so, the rate of increase of a bacterial population depends on conditions, in this case, increasing carbon increases bacterial biomass (I wonder if one gram of carbon results in some tenths of a gram of bacteria. Sounds like too much, there is predation and export as you point out.). And you are right, we typically donít fill our aquarium with bacteria, though that would be an interesting calculation. 40 gallons of bacteria equals how much vodka. However, when the nitrogen or phosphorous is used up, I am pretty sure the larger bacterial population has few choices if any but to die or form spores. I think to move forwards at this point we need to answer the question how many bacteria are generated from a mg of NH3. I donít know off hand what a typical bacterial stoichiometric ratio of elements is but assume 5% by weight is nitrogen. That gives 20 milligrams dry weight of bacteria. Spread throughout the aquarium that amount would be invisible, yes? And if skimmable, I would guess removed or diminished in number quite easily. There must be a portion lost through predation too.


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"Harvesting" is a bit ambiguous here.
I have macro algae on the brain


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I agree that a visible slime is one possibility. I'm not so sure that bacterial crashes are going to be a significant danger. Bacterial populations can increase quite rapidly, generally, so I'd expect that a crash would be undetectable with hobbyist equipment. Stopping feeding seldom seems to cause issues, for example, and it's actually a step that I often recommend when dealing with various nutrient buildup or tank crash situations.
If one suddenly stops dosing carbon and there is no ammonia spike, you have not killed off or severely impacted the systemís ammonia processing capability, i.e., no crash, right?

So where are we? Carbon dosing could impact autotrophs but we have little or no data to say this is a large downside. In principle, we should remove the extra bacteria we grow with carbon dosing to maximize nutrient export but this might not be totally necessary if that bacterial biomass is assimilated and locked up long term in some other biomass, e.g., the tanks population of protozoa, rotifers, amphipods, etc. Are we done here?


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Old 01/04/2018, 09:39 PM   #49
bertoni
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Isnít the notion of carbon dosing essentially growing bacteria?
Well, that depends on what you mean... The stated goal is to export phosphorus and nitrogen from the system by consuming them from the water column, and then out of the tank via the skimmer. That process could be accomplished by growing a fairly steady bacteria population that exports nutrients via skimming byproduct and the inevitable death and replacement rate, at least in theory. So a net increase of bacterial mass might not be required. Given that some people report dosing carbon for years, it's fairly clear to me that the tank reaches a relative steady state, possibly fairly quickly. Of course, export by skimming the bacteria themselves probably happens to at least some extent. I don't know of anyone who has surveyed the change in bacterial levels in the skimmate with carbon dosing, not over a long time frame, anyway.

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And if so, the rate of increase of a bacterial population depends on conditions, in this case, increasing carbon increases bacterial biomass (I wonder if one gram of carbon results in some tenths of a gram of bacteria. Sounds like too much, there is predation and export as you point out.). And you are right, we typically donít fill our aquarium with bacteria, though that would be an interesting calculation. 40 gallons of bacteria equals how much vodka. However, when the nitrogen or phosphorous is used up, I am pretty sure the larger bacterial population has few choices if any but to die or form spores. I think to move forwards at this point we need to answer the question how many bacteria are generated from a mg of NH3. I donít know off hand what a typical bacterial stoichiometric ratio of elements is but assume 5% by weight is nitrogen. That gives 20 milligrams dry weight of bacteria. Spread throughout the aquarium that amount would be invisible, yes? And if skimmable, I would guess removed or diminished in number quite easily. There must be a portion lost through predation too.
All interesting points. I personally would guess that there's a lot of mortality in the bacterial population. Viruses and other microbes are happy to kill or consume bacteria. If my memory is correct, the ocean has more viruses looking to infect bacteria than it has bacteria to infect. Our tanks might be similar.
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If one suddenly stops dosing carbon and there is no ammonia spike, you have not killed off or severely impacted the systemís ammonia processing capability, i.e., no crash, right?
That's possible. In addition, the ammonia-processing capacity might increase very rapidly in response to the input. At some point, we'll be arguing over wording here. The end result is the same.
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So where are we? Carbon dosing could impact autotrophs but we have little or no data to say this is a large downside. In principle, we should remove the extra bacteria we grow with carbon dosing to maximize nutrient export but this might not be totally necessary if that bacterial biomass is assimilated and locked up long term in some other biomass, e.g., the tanks population of protozoa, rotifers, amphipods, etc. Are we done here?
I am sure that carbon dosing will have some impact on autotrophs. I am skeptical about the downside being significant, given the experiences reported here. I think we're done, pending data on what is happening. That data is going to be very expensive to produce, I'd guess, which is too bad. It'd be interesting to see what's happening.


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Old 01/05/2018, 09:36 AM   #50
Dan_P
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Originally Posted by bertoni View Post
Well, that depends on what you mean... The stated goal is to export phosphorus and nitrogen from the system by consuming them from the water column, and then out of the tank via the skimmer. That process could be accomplished by growing a fairly steady bacteria population that exports nutrients via skimming byproduct and the inevitable death and replacement rate, at least in theory. So a net increase of bacterial mass might not be required. Given that some people report dosing carbon for years, it's fairly clear to me that the tank reaches a relative steady state, possibly fairly quickly. Of course, export by skimming the bacteria themselves probably happens to at least some extent. I don't know of anyone who has surveyed the change in bacterial levels in the skimmate with carbon dosing, not over a long time frame, anyway.
This seems like a reasonable high level description. I wonder if what you are feeding by carbon dosing takes over ammonia capture and export from the ammonia oxidizers-denitrifying system.

I would wager that the steady state that you posit above is reached when the ratio of carbon added to the food nitrogen added is at the correct ratio to favor near complete assimilation with little or no waste ammonia to be oxidized to nitrate. This is Belgian Anthiasí point. And when there is a reduced amount of nitrate, then maybe the denitrifying bacteria population is decreased, another Belgian Anthias point.

I have a fish only system with a lot of macro algae but periodic outbreaks of unsightly things (diatoms, cyanobacteria, dinoflagellates all IDíd under a microscope) BUT phosphates are usually undetectable and nitrates less than 0.5 ppm except for occassional unexplained short term nitrate spikes. PO4 and NO3 are poor perdictors of nuissance organism growth. So, I am wondering now based on this debate whether shifts in ammonia production-consumption might be a useful predictor, though impossible for me to measure. I might just try carbon dosing based of nitrogen input to see if the periodic nuissance growth goes away.

Dan


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