Over the last few years vodka dosing and organic carbon dosing has become a topic of interest within the ornamental aquarium community. On paper, it offers a relatively affordable, simple and inexpensive way of achieving high water quality when compared to traditional nutrient control systems. Typically, to achieve the water quality required for ultra low nutrient systems, equipment like ZEOlite reactors and  Biopelt reactors are used.
While the carbon dosing technique has been around for many years it has recently been revisited and made popular on online forums. The momentum grew as people started to share photos of the results they were achieving and the various techniques they were using. The techniques that have been developed today are largely based on trial and error by hobbyists and some aspects of the science behind it are still not entirely understood.
During the summer of 2014, I contacted renowned aquarium author Albert J. Thiel and asked if he would be interested in researching and compiling the most current information and best practices for vodka dosing. This article is the result.
I hope you find this a useful resource

Neill Wainwright 2014


Introduction to carbon dosing 

Organic Carbon dosing has been around in the Hobby for quite a number of years, yet few are those who actually use it, or fully understand how to safely implement organic carbon dosing using one of the several additives that can actually be employed to do so.
It could very well be that a lack of in depth understanding of how to safely dose, in the case of this article Vodka (one of many organic carbon sources), is the reason why so few Hobbyists actually implement this excellent method of lowering both Nitrate and Phosphate levels in their Aquariums, as well as increasing the coloration of their corals. The latter results are documented and confirmed in far too many sources to mention here.
The purpose of this review is to provide an explanation to those who are ready to start dosing Vodka in their tanks, and make sure they do so safely by imparting a good knowledge base on the matter in general.
Carbon is the fourth most common element in our world. It is unusual in nature as it has the ability to self-polymerize (getting monomers to combine to form longer so-called polymers) and, as a result, form long molecular chains.
Carbon’s abundance and its ability to form a wide range of polymeric structures allows this molecule to form other essential molecules found within all organisms.
Carbon is found within your reef aquarium as inorganic bicarbonate. When these carbon molecules are incorporated into more complex forms within cells they are termed "organic".
Adding certain organic compounds to our reef aquarium has been reported to lower Nitrates and Phosphates in our aquariums, as indicated earlier, and one such organic source is ethanol, best added in the form of Vodka.
Why Vodka will you ask. The reason is simple: it is a purer form of alcohol than many others such as whiskey, or similar alcoholic beverages, because no additives are used in Vodka, and no elements are added to give it color or a different taste, and Vodka is therefore  processed and distilled in a cleaner and purer form. As a result nothing is added to the aquarium that may, or could, be noxious to the fish and corals and other life forms we maintain in our tanks when you use it to "Carbon Dose".
How it works 
The addition of Vodka to the aquarium in small daily dosages has been found to increase the bacterial colonies in the tank (biomass). As Vodka is added bacteria continue to reproduce and their numbers increase. As this happens nitrate and phosphate and other nutrients dissolved in the tank's water are utilized in the formation of larger molecules that are needed by the bacterial population for growth and survival.
As these bacteria uptake nitrates and phosphates they obviously reduce their concentration in your aquarium' water, which is of course the reason why you are adding the carbon source to begin with (Vodka in this case).
Note that as the bacterial population grows, the amount of "skimmate" that is produced will increase as well, and will take on a different appearance and smell. The skimmer is needed to prevent that a bacterial bloom occurs in the tank which could have nefarious effects if the bloom gets out of hand. What I am saying is that you should not engage in carbon dosing if you do not have a skimmer installed on your aquarium, and it should be an efficient model to boot. Cheap units will not do a good job and may not keep the excess bacterial population under control.
If that happens, the water in the tank will get cloudy, or hazy, and if the excess of bacteria were to suddenly die off, oxygen levels in the tank would be greatly reduced, leading to a possible loss of fish and other life forms, or at best to your fish being stressed and breathing much more rapidly, and your corals not looking as healthy as they should.
Even if you do not have a bacterial bloom but just a large increase in bacteria, their oxygen consumption will have a tendency to lower the Oxygen concentration in your tank's water column, and good aeration by the skimmer will compensate for that.
Some have suggested using ozone and a controller to counteract diminishing oxygen levels but I have not found that to be necessary. Another option for those who wish to employ one is the addition of an Oxydator, a device that uses hydrogen peroxide and a catalyst to produce water and oxygen and raise the tank's O2 concentration. Again I have not found that to be needed, but it cannot hurt if you employ one of the two methods suggested (ozone and and/or an Oxydator).
Avoid this from happening by ensuring that you have an efficient skimmer installed on the tank, besides as will be explained later, dosing the appropriate and correct amount of Vodka each day, using in this case the medial dispensing pump that you have acquired or will acquire.
Note that the skimmate is said to not only remove "more" unwanted matter from the aquarium, but also the byproducts of the bacterial assimilation of nitrate and phosphate, which is what results in NO3 and PO4 concentrations dropping in the aquarium, which is the goal we had when we started using Vodka carbon dosing.
It is said that Vodka dosing increases, or can increase, the quantity of Yellowing Matter or Gelbstoff as it is often referred to, in the aquarium. Whereas, again, ozone would counteract that, all one has to do to deal with such a possible increase is to use some activated carbon to lower the amount of Yellowing matter which comes from the breakdown of organic material.


You may be wondering by now whether Carbon Dosing is actually safe, and that is indeed a concern you should have. Let me assure you that as long as you dose Vodka correctly and based on the suggestions made below, it is totally safe and will have many benefits for your aquarium:
  • reduction in nitrate to very low levels
  • reduction in phosphate to very low levels
  • reduction in the appearance of nuisance algae such as GHA
  • reduction or elimination of other undesirable algal growth
  • diminished amount of dissolved organics in the water
  • skimmer operating a greater efficiency
  • enhanced coloration of your corals

Photos published on Reef Central by Sonny Harajly in this post and kindly reproduced on this site with his written permission. 

Many more before and after photos are on display in the Reef Central online forums: Before and after photos. 

Dosing guide

So what and how much do you need to dose ?
First of all you will need to get some Vodka. Obviously from a Liquor store and hopefully you are of age to be able to buy it. Do not purchase the expensive brands, such is not necessary. You can buy the least expensive Vodka that you can find, and buy the 80 proof (40 % ethanol). There is in my experience no benefit in buying the high end brands. Just make sure you buy the pure variety not the one that has been spiked with some condiment or flavor.
The first and most important thing to do is to test your water with high quality tests that read in the low ranges for Nitrate and Phosphate and that are tests that are intended to be used on Saltwater of course. Make sure that the tests you buy have not expired and still have a good deal of useful or shelf life when you acquire them.

Why is this important?
So you know what your starting levels are, nothing more than that, but make sure your tests read accurate numbers. Repeat the test twice, or even three times, to make sure you get an accurate result and write those numbers down in a logbook, or in a file on your PC or Laptop. You will need those numbers to monitor how the addition of Vodka is affecting their levels and when to change the quantity of Vodka that is being added to your tank.
Next make sure you understand how to dispense the Vodka into your aquarium or sump if your set-up has one.
If you use a syringe pump read the instructions carefully, and realize that the setting on the back of the Pump is in millimeters and not in milliliters. You will need to measure how many mm (millimeters) you need to set the pump for so it dispenses the number of ml (milliliters) that you want the pump to add to the aquarium every 24 hours. Doing so is not difficult but that is a task you need to take care of.
How much that is exactly depends on the type of syringe you use. If you employ the one that came with the pump, the equivalent for instance is 1 inch = 8 ml. But do the calculation for yourself based on the amount you need to add. The recommended dosages are listed below.

After testing the next thing you need to do is figure out how much water volume is in your system.
That means total water volume including your sump (if any) and fuge (if any), and water in any other containers that are part of your system.
The difficulty most hobbyists run into is estimating what the water displacement is of the rock they have in their tank as that quantity needs to be deducted from what the total volume is that your tank really holds (and remember that your tank is not filled to the top), and if you have sand in the tank and/or rubble in the sump you will need to account for that as well.
If you cannot accurately figure it out go for a "safe" number. A number lower than what you think it is. Deduct a few gallons from what you came up with.
So now that we know that here are the suggested dosages, using 80 proof Vodka. The brand does not matter but as I said use an inexpensive one.

Dosing program  

  • Start dosing 0.2 ml per 25 gallons for 4 days
  • Day 5 to day 8 dose 0.3 ml per 25 gallons in the system
  • Starting day 9 dose an additional 0.5 ml per day regardless of how large the tank is and maintain that level for one week
  • If the nitrate and phosphate levels are not diminishing at that dose, add another 0.5 ml to the daily dose regardless of tank size
  • If the nitrate and phosphate levels are dropping maintain the dose you were adding and keep doing so until the levels become undetectable by the test kits you are using
  • Once the levels are undetectable reduce the dosage by 50 % and maintain that dose going forward but test your nitrate and phosphate levels to determine what they are
  • When you determine that the levels are rising again, add 0.2 ml of Vodka to the last dose you were using and do so for a week.
  • If the levels are still not dropping add another 0.2 ml and monitor the nitrate and phosphate levels every day
  • Once the levels drop back to undetectable levels reduce the current dosage by 50 % and keep monitoring your nutrient levels
  • Continue as above should the levels rise again till they drop once more, etc.

This may sound complicated but it really is not. All you need to do is test your nutrient levels and then follow the recommended dosage additions listed above.


Additional pointers

  • Only start Vodka dosing when the tank has cycled completely and has been running for about 2 months at a minimum
  • You should never see a bacterial bloom in your tank (hazy or cloudy water) and if that happens discontinue adding Vodka and do a large water change. Resume dosing once that situation is cleared up
  • Maintain your dKH at 7-8 at all times. This is important for the well being of your corals, especially SPS ones
  • Add an amino acid supplement to your tank, especially if your corals do not show increased coloration. Use a high quality product. You can add such a supplement even if your corals show good coloration but reduce the amount you add to about half of the recommended dose of the product you are using
  • Maintain your feeding regimen. Some say you can actually increase it somewhat since the carbon dosing will help to eliminate excess nutrients in the tank, but if you do so, increase the "number of times" you feed rather than the amount you feed each time you add food to the tank. Typically feeding 2, and preferably 3, times a day is recommended
  • Water quality will improve when using carbon dosing. If it does not you may be overdosing and have some haziness and need to reduce the amount you are adding. Alternatively you may have Yellowing of the water and you may need to use GAC (granulated activated carbon) if you are not already doing so
  • Again get the least expensive Vodka you can buy but make sure it does not contain any flavor additives



This overview of Vokda dosing will hopefully allow you to implement the method successfully.
Happy reefkeeping
Albert J. Thiel

About the author 
Albert J. Thiel is the founder of legendary Thiel AquaTech (Active during the 90's) and a pioneer of many of the current reef keeping methods widely used today. Albert has been invited as a guest speaker to may international aquarium conferences and In 1989 he published possibly the first book on what we now call ‘nano reefing’ entitled, Small Reef Aquarium Basics – for smaller tanks and for beginner hobbyists. Other notable works include  The Marine Fish and Invert Reef AquariumAdvanced Reefkeeping IAdvanced Reefkeeping IIThe New Marine Fish and Invert Reef Aquarium.