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The vodka method


As all healthy ecosystems are based on the natural limited availability of organic carbon, I was skeptic about carbon dosing since the beginning and have collected and sheared information since then.

With the knowledge we have gathered so far concerning corals and the coral holobiont I will consider the use of carbohydrates as ethanol in a reef aquarium as dangerous until the contrary is proven. The addition of carbohydrates must be done with knowledge and can only be advised to people with enough basic knowledge and who understand the consequences of improper dosing of carbohydrates and especially of improper stopping dosing. Reading this article can help with this. #1)

In 2008 Ken S. Feldman an Kelly M. Maers warned about increased organic carbon availability. This is more as a decade ago! In an article published in the Advanced Aquarist they wrote:“circumstantial evidence encouraged Rohwer et al. to speculate that the introduction of carbohydrates (= a fuel source) will generate an imbalance in the bacterial component of the holobiont, and that this departure from equilibrium leads to coral mortality. The mechanism by which this induced bacterial proliferation causes coral death remains to be elucidated, and this pivotal issue must be addressed before this intriguing hypothesis can gain further traction. Nevertheless, the empirical evidence can be construed to support a robust relationship between elevated DOC levels, correspondingly increased bacterial populations, and coral mortality.” They also wrote:“ Reef bulletin boards all too frequently contain threads that begin “Help! My tank is crashing; my corals are dying, but all of my measurable water parameters are within expected ranges. What's wrong?” Could it be possible that elevated levels of DOC, for whatever the reason, are contributing to, or even causing, the coral loss? (FeldmanEnMaers2008>Feature Article: Total Organic Carbon (TOC) and the Reef Aquarium: An Initial Survey, Part I”. Page. .

In the meantime this has been confirmed by many scientific publications, but people continue to promote and advise all kinds of products based on organic carbon, considered safe to be used in a reef aquarium.
Many dose organic carbon without knowing it as it is not always on the package and the seller fails to point it out. In that case, the user certainly does not know what the possible consequences may be of the product sold as “safe”. Purchase and use of such products is therefore highly discouraged.

Removal of nitrate and phosphate by adding organic carbon

In the first place an assimilation method used to lower the nitrate and phosphate level in the water column by dosing organic carbon compounds. Can also contribute to an increased heterotrophic denitrification capacity. Sometimes vodka is used for this because it contains ethanol. Also when other carbohydrates are used, the name vodka method is usually used. Dosing carbon hydrates for the production of protein may also be used to sustain planktonic growth.
Heterotrophic bacterial growth is limited by the availability of suitable organic carbon. Heterotrophic bacterial growth is stimulated, as a result of which the growing bacteria extract nitrogen and phosphor (and all other necessary building materials) from the water column, necessary for their cell synthesis and survival. The intention is for these bacteria to be harvested by the present skimmer so that nitrogen and phosphor (and all other building materials) are effectively removed. The biomass (protein) cultivated this way that is not removed in time will become part of the normal food chain, eventually have to be mineralized, after which nitrate is produced.
The administration of supplemental organic carbon is considered safe and not harmful by the protagonists.

The role of organic carbon in relation to the growth and survival of corals is discussed in detail in a contribution about the coral holobiont.

Since only carbohydrates are added, the redevelopment of the building materials available in the aquarium is achieved by the rapid growth. Since nitrate and or phosphate build-up may be caused by a shortage of other essential building materials, which are constantly removed by the skimmer, one will have to think about the consequences of it before starting to add carbohydrates. Where do the necessary building materials come from? Nitrate is a harmless nitrogen compound. Since the cause of nitrate build-up is known, it is also very easy to remedy. If it is assumed that the nitrate-nitrogen is not needed, it is better to export it than assimilate. Take your decision only after reading this article. CMF De Haes 2018)

It should be borne in mind that bacterial heterotrophic growth not only takes up nitrogen and phosphorus for cell synthesis, but that obtaining the energy necessary to do so results in the production of carbon dioxide, nitrogen and phosphorus. In some cases, heterotrophic bacterial growth results in more nitrate and phosphate being produced than what is eventually removed. In order to be removed, the protein produced by assimilation must be included in the food chain and, sometimes after many different intermediate steps, eventually end up in the end user, or actively removed by harvesting in time. Since a skimmer harvest only about one third of the organic substances, it is not inconceivable that the final yield of the administration of organic carbons can be negative, especially when compared with assimilation by photo-autotrophs of which much more ends up directly in the end user and which are much easier to actively harvest.
An explanation in English concerning respiration and growth ”Bacterial remineralization and respiration“ which gave me more insight into the event. MattChurch2019)

C/N ratio-induced structural shift of bacterial communities? It is a pertinent question whether it is possible to modify the composition of a microbial community in an environment like a biological filter, in which direct microbe controlling systems (e.g. water exchange, UV disinfection, etc.) are not really effective. In this work, we demonstrated that carbon concentration in water not only affects the nitrification efficiency but also the microbial community structure. This strengthens the idea that increasing the carbon removal efficiency will reduce the risk of proliferation of fast-growing r-strategist bacteria, eventually including pathogens, but surely consuming oxygen, clogging filters and releasing potentially harmful substances. MichaudEnCo2014) One of many papers about the effect of the C:N ratio on the live and balance in a closed community.

As bacteria primarily use ammonia-nitrogen, the C: N ratio is determined in relation to the total amount of ammonia-nitrogen (TAN Total Ammonia Nitrogen), ammonia + ammonium, and no consideration is given to any nitrate nitrogen.
Nitrate nitrogen is of little or no importance for the carrying capacity of the aquarium system. The export of nitrate nitrogen through denitrification does not affect the carrying capacity. The reduction of nitrate by heterotrophic assimilation has no direct influence on the supporting capacity, but indirectly because of the relatively high need for building materials and oxyen.

A distinction must be made between nitrate reduction and ammonium reduction. The addition of hydrocarbons primarily results in ammonium reduction.

Assuming that dosing carbohydrates reduce nitrate is a wrong approach to reality! Since in reef aquariums and certainly in so-called LNS (Low Nutrient Systems) the limited amount of ammonia normally produced is used very quickly, at the moment it becomes available, the least addition of carbohydrates will increase the C: N ratio. The C: N ratio is kept low by nature since the carbon is converted from organic matter into CO2. In a seawater aquarium, carbon compounds may constantly removed by a skimmer.

The understanding of the system is one of the key factors in the management of RAS (Recirculating Aquaculture Systems), as this requires interaction between engineering and organism biology and husbandry. All the key biological mechanisms involved in the functioning of RAS, therefore, need to be understood and mastered. This is particularly the case processes determining the development of bacterial populations and their interactions (Blancheton et al., 2013)
At high C/N ratios the heterotrophic bacteria reduce the diffusion of nitrogenous substrate and DO to the autotrophic nitrifying bacteria, thus negatively affecting the nitrification rate (Nogueira et al., 2002; Chen et al., 2006).
Reduction in TAN (Total Ammonia Nitrogen) removal rates as high as 70% has been reported at C/N ratios above 1 for dissolved carbon (Zhu and Chen, 2001; Ling and Chen, 2005), while a reduction of 73% has been reported at a C/N ratio of 2 for particulate carbon (Michaud et al., 2006).
Fast-growing bacteria (r-strategists) are the first to exploit an increase in substrate supply but, if the resources are consumed, they can be gradually outcompeted by slower-growing specialists (K-strategists)(Hansen and Olafsen, 1999).
The accumulation of biodegradable organic carbon in the water of aquaculture systems supports the heterotrophic activity and allows the establishment of competition mechanisms for oxygen, nutrients and space between chemoautotrophic nitrifiers and heterotrophs, causing a reduction of the nitrification rates (Zhu and Chen, 2001; Michaud et al., 2006).

What happens when organic carbon is dosed in an aquarium in which a phosphate absorber is used?
Can organic carbon be dosed without adding the other necessary building materials and what is the effect on the growth of corals and other residents when they have to compete for the same building materials? It is an important point of attention, especially when using biopellets.

It was determined that a skimmer can not remove all types of bacteria so that the part that is not consumed will eventually become part of the total amount organic compounds (TOC) A problem that is not seen is the fact that natural competition is disturbed because the same type of bacteria are left behind and have the opportunity to get adapted to changing circumstances and many other species not since they are removed, creating an unbalance between competitors. Scientists ask questions about the possible long-term consequences. Alternatives for a skimmer?

A good skimmer removes a maximum of + - 35% of the TOC present in the water and is very selective in the removal of bacteria. FeldmanMaers2010)

Some bacteria have the property to store more nitrate and phosphate than necessary, for later use when deficiencies arise. Only I do not know which strains are being skimmed and which are not.

An article in explains the defensive and progressive vodka method and also the VSV (Vodka Sugar Vinegar) method.Dieleman2014) In this article the doses are also based on the nitrate level and do not take into account the daily ammonia input for determining the dosage of carbohydrates, in the case of vodka, ethanol. In my opinion, a correct dosage is only possible if one has an idea of ​​the daily amount of NH4-N produced. When a little bit more than the daily contribution to the nitrate level is removed, the level will go down. This way, overdosing can be prevented so that no shortage of nutrients will occur and C:N ratio stays at an acceptably low level.
Overdose can lead to a high C/N ratio, causing heterotrophic bacteria to displace autotrophs. Heterotrophs grow about five times faster than autotrophs. With sufficient organic carbon, most of the ammonia will be assimilated by heterotrophic ammonium reduction whereby biomass (protein) are produced. To convert the same amount of NH4-N, 40 x more biomass is produced heterotrophically than in an autotrophic manner (nitrification).EblingEnCo2006-06) At the same time, nitrate will not be supplied fast enough in places where heterotrophic denitrification takes place, with the result that sulfate reduction can occur due to the need for an oxygen source. A biofilm can produce sulfide because of insufficient nitrate availability, because in a balanced biofilm HS is converted into sulfur or sulfate by sulphur bacteria for which nitrate is required which is converted to nitrogen gas N2 and is removed in this way. It is a normal part of the operation of a biofilm and of the denitrification process.

It goes without saying that this can have consequences in a ZMAS and not only when the produced biomass is not removed or consumed in time. When biofilters are used, it may lead to blockages, clogged filters.
A combination of BADES with VODKA is not recommended.

Users of an assimilation method such as the vodka method, biopellets and carbon-based heterotrophic denitrators may be confronted with a phosphate deficiency (notwithstanding that phosphate is present in the water column, there may be shortages due to competition, in a limited space such as in reactors) because the much higher biomass production. The assimilation of nitrogen is slowed down and is no longer proportional to the dose. If insufficient nitrogen is absorbed in relation to the carbon dose, the dosage is increased in many cases, resulting in a high C: N ratio, which causes explosive growth of biomass when sufficient phosphate becomes available, for example after feeding, and increased competition between the various residents for the phosphate made available and other basic elements. DeHaesCMF2016)

How much NH4-N is produced daily depends in the first place on the daily amount of food and its composition in% protein. Assuming that all food is consumed, a conversion can be made to the NH4-N production as explained here.

The C / N content also largely determines the ratio of autotrophic and heterotrophic denitrification in BADES reactors. In denitrators without sulfur addition, it is a limiting factor.

Dosing organic carbonaceous substances is an application that can help to keep nitrate build-up in nutrient-poor aquariums under control. Certainly when the dosage is limited to what is really needed to prevent build-up . When too much is dosed or when the aim is high assimilation and thus high growth there is a risk of the temporary or total loss of the existing biological balance by disrupting or interrupting the existing nitrogen cycle due to the influence on nitrification and denitrification, soil life and live rock. At high doses and a nitrate-nitrogen shortage for cell building, the nitrogen will be extracted from all available ammonium , ammonium reduction, where no more nitrate is formed, but 40X more bacterial growth than when the same amount of ammonia is reduced by nitrification. EblingEnCo2006-06) Knowing that only a small part of this can be removed by a skimmer should be taken into account.

Before using the VODKA method (assimilation method) it is important to know how much the daily ammonia production is about. This can be derived from the amount of food provided and its composition (% protein) or by measurements of the evolution of the nitrate content. In order to lower the nitrate level, only a little more than daily nitrogen overproduction needs to be removed daily. A small dose enough to assimilate the nitrogen overproduction will result in the nitrification capacity is reduced only a bit, making nitrification more effective.

The vodka method gives me no control over the event. We add substances to the water that do not naturally occur in seawater, such as vinegar, sugar and vodka, and the effect of which is not known in the long term.FeldmanMaers2008-08) FeldmanMaers2008-9)

Dieter Brockman, one of the driving forces behind the Berlin method, said in an interview with Roger Vitko in 2004: “The Internet is as much a curse to hobbyists as it is a blessing.” It contains many false statements and badly thought out hobbyist “experiments” accepted as fact. RVitko2009-09)] In particular, he meant adding vodka in a reef aquarium as an example, citing that such experiments have no place in responsible reef keeping, and that safe carbon sources already exist, if they are needed.
The amount of nitrate and phosphorus that is effectively removed can not be estimated in advance and the system relies entirely on a third pillar,the skimmer, of which is known it only selectively removes microorganisms. On top of that, the fact that only those organisms in the water column are eligible to be removed. Desired and undesirable organisms are stimulated as well as the formation of the bacterial film in undesired places with disruption of nitrification and denitrification as a result. A correct dosage is difficult and time-consuming.

Think before you start!

We know through extensive and thorough scientific research, among others by the Department of Chemistry of The Pennsylvania State University that only about 25% to 35% of the organic carbon present, depending on the skimmer used, is removed. FeldmanMaers2010) Part of it comes from microorganisms and also contains P and N. FeldmanEnCo2010-02) It has been proven that a skimmer removes nutrients from the water column. But only selectively.

The bottom line with regard to the hypothesis of carbon dosing is clear; the basic principles of this theory seem to be maintained in an experimental test. The dosing of carbon increases the bacterial population in the water column. And skimming removes bacteria along with the stored nutrient reserves. The scientific basic principle of this application has come true. This when all building materials are sufficiently available? FeldmanEnCo2011)

In the sea, the necessary building materials are present in very low quantities, but the supply is inexhaustible. In a ZMAS care must be taken to ensure that there is no shortage due to addition and / or water changes made with a suitable salt mixture.

An article appeared in that tries to create light in the darkness: Vodka Dosing…Distilled! A Powerful Method for the Reduction of Nitrates and Phosphates within the Reef Aquaria by Nathaniel A. Walton (Genetics) and Matt Bjornson (Stony_Corals)
The article starts with a warning: The following information is provided for your consideration in regard to a topic that has been questioned by some of the best minds in the hobby. The goal of this column is to compact many threads interested in a particular discussion to a user-friendly layout. The information contained in these articles is here to help educate and hopefully enhance the hobby while helping you to make informed decisions on aquaria upkeep. The author(s) assumes no responsibility for any consequences that may arise from the use of this information.WaltonEnBjornson2008-08)

Much reading pleasure:

Also in this article one does NOT take into account the daily nitrogen production and therefore it does NOT show how much of a carbohydrate needs to be dosed to lower the level.

In a normally fed aquarium about 1/3 of the produced ammonium will be reduced by heterotrophs which use the organic carbon present in organic waste originating from, among other things, excrement and urine and 2/3 autotrophic by nitrification, using alkalinity or carbonate from the substrate as carbon source. Depending on the composition of the supplied food, the C: N ratio, little waste will remain. The growth of the heterotrophs is limited by the availability of usable organic waste which completely removes the latter, it is the limiting factor for heterotrophic growth and for the heterotrophic assimilation of nitrogen and phosphorus. What happens if this balance is disturbed by a high availability of organic carbons not from organic waste? What if organic carbon is no longer the limiting factor for fast heterotrophic growth but phosphourus or nitrogen? Will organic waste still be processed? In the event of a shortage of phosphate in the water column, growth will cease, be heterotrophic and autotrophic including corals and its holobiont.


Het doseren van koolhydraten of het ter beschikking stellen via bioballen heeft tot gevolg dat de biomassa in het aquarium stijgt indien voldoende basisstoffen aanwezig zijn. Er wordt niets van de geproduceerde proteïne effectief verwijderd uit het systeem, uitgezonderd het deel van het deel aanwezig in de waterkolom dat kan worden verwijderd door een afchuimer. +- 25%.
Om 1 gram stikstof te assimileren wordt er +- 8 gram proteine geproduceerd, dit komt overeen met ongeveer 20 gram voedsel met een proteïne gehalte van 35%. Het toevoegen van deze hoeveelheid voedsel produceert +- 4ppm nitraat in een 1000 liter aquarium. Daar slechts een deel wordt verwijderd moet het overgebleven deel worden geconsumeerd. De consummatie als voedsel heeft tot gevolg dat 80% wordt uitgescheiden als ammoniak NH3 dat in zeewater grotendeels wordt omgevormd naar NH4 dit NH4 wordt genitrificeerd naar NO3 waarna de kringloop van het doseren kan herbeginnen. Daar bij elke doseringcyclus nitrificatie plaats heeft dit een grote invloed op de alkaliniteit. Dit kan zo blijven doorgaan zolang er voldoende groei mogelijk is om de proteïne productie te consumeren.Na een tijdje doseren van koolwaterstoffen kan men niet meer bepalen of dat het stikstof dat wordt geassimileerd door de dosis van natuurlijke oorsprong is of afkomstig van een vorige dosering.
Bij het gebruik van bioballen is de cyclus meestal van NH4 naar NH4 door heterotrofe ammonia reductie wegens de hoge beschikbaarheid van organische koolstof en dus door een hoog tot zeer hoog C:N ratio. Daar er geen nitraat wordt geproduceerd heeft er ook geen nitrificatie plaats wat als een voordeel kan worden aanzien zolang er voldoende fosfaat beschikbaar is. Door de zeer grote aangroei van biomassa is dit om moeilijkheden vragen, zeker op lange termijn.

Het moet de bedoeling zijn bij het doseren van koolwaterstoffen in de waterkolom om de C:N verhouding laag te houden en op deze wijze heterotrofe ammonium reductie te beperken waardoor voldoende nitrificerende capaciteit aanwezig blijft. Hierdoor wordt het risico dat door toepassing van biopellets aanwezig is beperkt of verwaarloosbaar.

Wanneer een concentratie van 20ppm nitraat aanwezig is en er wordt dagelijks 1 ppm nitraat toegevoegd dan is het voldoende om de dagelijkse dosering te baseren op 1,2ppm om het nitraatniveau te laten dalen. Daardoor blijft de C:N verhouding relatief laag.

Wat moet er uiteindelijk gebeuren met de biomassa die door regelmatig of continue doseren van koolwaterstoffen wordt opgebouwd? Maar geldt dit niet in mindere mate voor elk aquarium systeem? Het doseren van koolwaterstoffen wordt veel toegepast in zero emmissie aquacultuur systemen zoals het Belize systeem. Bij deze systemen wordt de biomassa na verloop van een bepaalde tijd geoogst!

Ik beschouw de methode als een onderdeel van de voedselketen die wanneer juist toegepast kan bijdragen aan het vinden van een balans. De op deze wijze geproduceerde proteine moet dan worden gebruikt voor de groei en het in stand houden van een planktonpopulatie die geschikt is voor de voeding van vissen en andere dieren zodat weinig of niet meer moet worden bijgevoederd. Voldoende plaats waar deze organismen zich kunnen verbergen om een populatie in stand te kunnen houden is dan ook nodig. Dit kan door het toevoegen van een refugium.


Carbon dosing redistributes the availability of nitrogen compounds and other elements !. If nitrate is reduced directly due to carbon dosing the system is overdosed and most ammonia will be used for heterotropic growth this way installing a very unstable situation by shifting the carrying capacity from autotrophic to heterotrophic ammonium reduction. It is a choice to make but I prefer the stability of a balanced system instead of being dependable of daily doses and human error. It may be a fact that when organic carbon is added to the aquarium the amount of nitrate present in the water may reduce but it is very unlikely nitrate is reduced directly by carbon dosing when dosed correctly. Only when a to high C:N ratio is maintained one may expect nitrate is assimilated directly. Carbon dosing will deplete the ammonium content making it unavailable for other users and this may be considered a good or a bad thing. For me it is a bad thing.
Why nitrate may build up in a brightly lit aquarium and is not consumed by photo- autotrophs which do not need any organic carbon and have an unlimited energy source? This when phosphate is present! Insufficient availability of other building materials may be a logic conclusion!? But when organic carbon is added, suddenly all the necessary building materials are available even enough to create a bacterial bloom! This means the by carbon dosing promoted bacteria use up the building materials which in normal conditions are used by other organisms. And there is no prove any of the nitrogen used is retrieved directly from nitrate but it may ! As the total of available building materials for growth theoretically stays the same, exempt for carbon, they stay limited available and there is no reason to believe that suddenly there is enough to assimilate also all the available nitrate, something which the photo-autotrophs where not able to. Most probably the nitrate level is reduced by denitrification and DNRA as the nitrate production is limited due to the reduction of the nitrifying capacity. Hopefully some photo-autotrophs may help! The denitrification capacity and nitrogen export of nitrifying bio-films will be lost.
This when the availability of organic carbon is not overdosed as by overdosing a lot of building materials may become available due to the decay of the organisms, responsible for to keep the balance, which are now replaced. And they contain nitrogen!

It should not be a problem for lowering the nitrate level by adding supplemental organic carbon promoting the assimilation of Ammonium-nitrogen when the addition is limited to the amount needed to assimilate the daily nitrogen overproduction or just a little bit more.

For exporting nitrate one may make use of BADES or manage algae growth in a refuge.

CMF De Haes 2017 -2018
Alle rechten voorbehouden

#1) CMF De Haes 2019-10
MichaudEnCo2014) Michaud, Luigi, Angelina Lo Giudice, Filippo Interdonato, Sebastien Triplet, Liu Ying, en Jean Paul Blancheton. “C/N Ratio-Induced Structural Shift of Bacterial Communities inside Lab-Scale Aquaculture Biofilters”. Aquacultural Engineering 58 (januari 2014): 77–87.
FeldmanMaers2010), FeldmanMaers2010) Feature Article: Further Studies on Protein Skimmer Performance - Advanced Aquarist | Aquarist Magazine and Blog [WWW Document], n.d. URL
Dieleman2014) De Wodka-methode - Bestrijding van nitraat- en fosfaat-overschotten in het zeeaquarium – versie 2014 [WWW Document], n.d. URL
EblingEnCo2006-06), EblingEnCo2006-06) Ebeling, J.M., Timmons, M.B., Bisogni, J.J., 2006. Engineering analysis of the stoichiometry of photoautotrophic, autotrophic, and heterotrophic removal of ammonia–nitrogen in aquaculture systems. Aquaculture 257, 346–358. doi:10.1016/j.aquaculture.2006.03.019
FeldmanMaers2008-08) liquid, n.d. Feature Article: Total Organic Carbon (TOC) and the Reef Aquarium: an Initial Survey, Part I [WWW Document]. URL .
FeldmanMaers2008-9) liquid, n.d. Feature Article: Total Organic Carbon (TOC) and the Reef Aquarium: an Initial Survey, Part II [WWW Document]. URL .
RVitko2009-09) A History of the Hobby by Roger Vitko - [WWW Document], nd URL The Internet is as much a hobby of hobbyists as it is a bean, it is a hobby and it is not easy to think about hobbyists who are accepted as fact. an example, citing that such experiments have no place in responsible reef keeping, and safe carbon sources already exist if they are required.
FeldmanEnCo2010-02) Feature Article: Elemental Analysis of Skimmate: What Does a Protein Skimmer Actually Remove from Aquarium Water? - Advanced Aquarist | Aquarist Magazine and Blog [ WWW Document], nd URL
FeldmanEnCo2011) admin. “Feature Article: Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration”.
WaltonEnBjornson2008-08) Vodka Dosing by “Genetics” and “Stony_Corals” - [WWW Document], n.d. URL The following information is provided for your consideration in regard to a topic that has been questioned by some of the best minds in the hobby. The goal of this column is to compact many threads interested in a particular discussion to a user-friendly layout. The information contained in these articles is here to help educate and hopefully enhance the hobby while helping you to make informed decisions on aquaria upkeep. The author(s) assumes no responsibility for any consequences that may arise from the use of this information.
en/makazi/het_water/filtratie/vodka.txt · Last modified: 2020/08/07 12:35 by matricaria
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