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What Is Vodka Dosing in a Reef Tank and Why Do We Do It?

I’ve heard a lot about people who add vodka to their aquariums. Yes, the very same Russian (or any other) vodka. But what vodka dosing is, and why is it carried out? An aquarist friend told me that vodka reduces nitrate and phosphate levels. Let’s see if his advice holds.

What Is Vodka Dosing?

Vodka dosing is a method used to remove nitrates and phosphates with an aid of special bacteria. To stimulate the growth of these bacteria populations as carbon sources, certain amounts of ethyl alcohol (vodka) are added to the water. The excess of the growing bacteria is removed from the aquarium by flotation. Water flotation removes organic impurities and excess bacterial mass from the aquarium (produced by the use of filters).

Interesting fact: Vladimir Vysotsky sang this process in his bardic hit: “And I poured vodka in the aquarium, drink, fish, for my birthday”.

Why is Vodka Dosing Used?

Vodka dosing is used as a preventative or countering remedy. When nitrates in your tank are freaking out, dosing vodka may help. There are only four main causes for high nitrates in the aquarium, which are true in 95% of cases. Let’s list them in descending (more frequent first) order:

  • Overfeeding
  • Poor blowing
  • Overcrowded display tank
  • Ammonium outbreak


Do you always think your fish are hungry? Do you think your corals will die without daily feeding? Do you feed your fish twice a day or more and still want more? Stop it now!

Poor water flow

If the aquarium enjoys insufficient flow, (or organization is poor, resulting in stagnation) there will certainly all kinds of debris: food wastes, fish poops, etc. Debris begins to rot, starting a nitrogen cycle, which ends in a high level of nitrate. Properly adjusted water flow washes the wastes all the way into the sump, and protein skimmer. Flow is important to start decomposition within your display tank.

Overcrowded display tank

Remember I’ve said that nitrate appears at the end of the nitrogen cycle? The decomposition of organic matter establishes a domino effect. Fish food & excrements are the greatest contributors. Therefore, the more fish you have, the more organics will be at the start of the nitrogen cycle.

Ammonium outbreak

When a large anemone or fish dies in the tank, and that large something has time to decompose before you notice this fact, you will definitely end up with an increase in nitrate.

Important theory

Yet there is another reason for high nitrates in the tank  —  it’s a small colony of nitrifying bacteria involved in biological processes in your aquarium. 

The nitrogen cycle can be described as follows:

  1. Fish products + food residues = ammonia (NH3/NH4)
  2. Ammonia + aerobic (nitrifying) bacteria = nitrite (NO2)
  3. Nitrite + aerobic (nitrifying) bacteria = nitrate (NO3) 4.
  4. Nitrate + denitrifying bacteria = gaseous nitrogen (N2)

This is a very simplified scheme, chemically there are much more chains and splits, but the main thing for us is to get the whole picture. Only the 4th stage has particular meaning within this article  — how to “feed” or remove the nitrate to the state of non-toxic compounds.

That’s exactly the moment where the vodka dosing enters the room, or more specifically, carbohydrates dosing. Fighting nitrates with fast carbohydrates is an effective way to stabilize the equilibrium with the reef tank.

Often on forums and in articles, you can find methodologies for dosing vodka/vinegar/glucose in a saltwater aquarium. By and large, all these substances are carbohydrates in a rapidly degradable form, which are food for nitrifiers and denitrifiers. Vodka dosing can quickly build up colonies of wage-war bacteria that break down nitrate. Thus, you can use vodka dosing if you have serious nitrate problems that require immediate intervention.

To dose or not to dose: Vodka dosing, is it the answer?

Vodka is capable of showing remarkable results, but the downside of this method is, as soon as you stop pouring carbs into the tank, the nitrate level is 90%  —  back to the old levels. It is clear from many observations that vodka is a short-term solution. To solve a serious nitrate problem, you are better off using another method. Especially considering the statements of some scientists about the development of fish addiction to vodka. I’m not telling you have to be Debbie Downer but you indeed want your fish to have their party dry.

Here is how you can ward off nitrates except by vodka dosing:

  • Partial water change + proper water flow
  • Charcoal, Protein Skimmer, and other adsorbents
  • Feeding fish and corals
  • Bacteria dosing
  • Nitrate adsorbent formulations 
  • Chaeto/Scrubber
  • Soft corals cultivating

Partial water change + proper water flow

Nitrate can not precipitate, and its entire concentration is directly in the water. Accordingly, a partial water change (50%) will reduce the NO3 concentration by half. This is a short-term solution, but at very high levels (above 70 mg/liter), the change is an excellent way to unload the fish and invertebrates until the cause of stress is known.

Charcoal, Protein Skimmer, and other adsorbents

Putting charcoal in the aquarium permanently allows you to absorb some of the organics at the start, and therefore the amount of nitrate in the output. Adsorbents pull all substances from the water (phosphate, nitrate, silicates, etc.) however, they have to shield even harder than 9 to 5 to provide decent protection from nitrates. Because adsorbents do not address the causes of nitrate. If you are willing to constantly buy an adsorbent and replace it every three months, your nitrate levels will be zero.

Feeding fish and corals

Halve your fish food dosage, feed your corals no more than once a week, and leave fish without food on the day of feeding. Believe me, your animals will not starve to death. It will die much faster from high nitrates than from feeding spartan. Once you have a stable nitrate level in the system, gradually add more food, testing for nitrate. This way you will find a happy medium for your feed volume.

Bacteria dosing

Prodibio and some other manufacturers offer bacteria ampoules among their products. Each ampoule contains about 2 million denitrifying bacteria, which, once in your aquarium, begin to create large colonies of their own kind. In this way, you increase the number of bacteria that can break down nitrate to nitrogen. A reliable method, but not a fast one.

Nitrate adsorbent formulations 

In 80% of the cases, liquid nitrate-absorbent formulations in the aquarium are the same as fast carbohydrates. Either find 20% of the rest products or consider another method.


Primitive algae are known to consume large quantities of nitrate for growth. When it is freely available, some algae (thread algae, moss, seaweed) grow rapidly, creating an unaesthetic aquarium. Chaeto, Caulerpa, and some other plants do the same, but faster. Installing an algae tank in the sump is a great and long-lasting solution to fight back nitrates in the water. As the heta grows, it “pulls” nitrate and phosphate from the water.

Hint: algae require some time investment. As it’s not always easy to consider every major aspect of dealing with algae. Such as lighting, phosphate levels in the water, the amount of Chaeto in the compartment, etc., but that is a topic for a separate material.

Soft corals cultivating

Soft corals (devil’s hand corals, xenia, some leather corals, etc.) also require nitrate for growth. Even though they consume it more slowly and in smaller amounts than primitive plants… they still consume it.

If you want to pick beginner-friendly soft corals, check out this selection. I’ve picked TOP 11 soft corals of all talks.

You can mount frags of various soft corals. They will consume nitrate from the water for their growth, reducing the overall NO3 level. Once the biological equilibrium in the tank is established, these corals can be kept or sold/distributed. Bear in mind: this is a slow way to neutralize nitrates. 

Should You Use Vodka Dosing?

I find this method more suitable for more experienced aquarists than for beginners because beginners often find it difficult to recognize from corals how they react to the addition of alcohol. Experienced aquarists, on the other hand, have already learned the reactions and the appearance of healthy aquarium inhabitants and will be able to react in time to help them if needed. 

How much vodka do you need?

You can start with 1-2 ml daily and then increase the dosage by 0.5 ml every week. In this way, over a year of such manipulations, you will need about 3-4 liters of vodka. 

What can you do instead of vodka dosing?

If you’re experiencing nitrates above 50 mg/l, consider the following:

  1. Halve fish feeding, feed corals once a week
  2. Check the water flow and protein skimmer
  3. Perform 20-30% water changes twice a month 
  4. Put an algae tank (if there is samp). If you already have an algae tank, and nitrate does not fall, check the lights in it
  5. Cultivate soft corals. Even a couple of frags can make the difference
  6. Every two weeks, dose an ampoule of Prodibio Biodigest or any other marine bacteria of your choice.