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01/02/2018, 07:40 PM | #26 | |||
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01/03/2018, 02:02 AM | #27 | |
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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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01/03/2018, 03:10 AM | #28 | |
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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. Last edited by Belgian Anthias; 01/03/2018 at 06:32 AM. |
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01/03/2018, 04:28 AM | #29 | |
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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. Last edited by Belgian Anthias; 01/03/2018 at 08:52 AM. |
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01/03/2018, 05:04 AM | #30 | |
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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). Last edited by Belgian Anthias; 01/03/2018 at 05:27 AM. |
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01/03/2018, 05:50 AM | #31 | |
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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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01/03/2018, 11:50 AM | #32 | |
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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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01/03/2018, 02:25 PM | #33 | |
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01/03/2018, 02:53 PM | #34 | |
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01/03/2018, 02:54 PM | #35 | |
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01/03/2018, 05:18 PM | #36 |
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1) “All this implements a very low nitrification and denitrification capacity.”
2) “An 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.” 3) “Once started dosing it may be difficult to stop” 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 system’s 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 beginner’s 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 “never change or do anything quickly to an aquarium”. Has anyone suddenly stopped dosing carbon and observed what happens? Maybe not. Good discussion so far. Dan |
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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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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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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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. |
01/04/2018, 04:57 AM | #41 | |
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The way it is done is irrelevant?
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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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01/04/2018, 05:40 AM | #42 |
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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. |
01/04/2018, 02:20 PM | #44 | |
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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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01/04/2018, 02:22 PM | #45 | ||
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01/04/2018, 07:27 PM | #46 | |
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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? 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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01/04/2018, 08:04 PM | #47 | ||||
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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. Quote:
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01/04/2018, 08:42 PM | #48 | |||
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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? |
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01/04/2018, 09:39 PM | #49 | |||
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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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01/05/2018, 09:36 AM | #50 | |
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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 Anthias’ 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 ID’d 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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