Reducing Nitrates in Your Marine Aquarium With the Vodka Method

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Is it really possible that sharing a very dry vodka martini with your saltwater aquarium can reduce your nitrate (NO3) and phosphate (PO4) levels? Marine aquarists have experimented with the "Vodka Method" (currently called "Probiotics") for some time with varying reported results.

How It Works

In the Q & A section of the September 2010 issue of Aquarium Fish International, marine biologist Charles Delbeek explains: "The 'Vodka Method' is a means to add inorganic carbon in the formed alcohol to cause bacteria to grow. In boosting bacterial growth, nitrate and phosphate are incorporated by the bacteria, lowering these values in the water. The excess bacteria are then either removed through skimming or are consumed by other organisms, such as sponges."

Delbeek went on to explain that he has used this method for short periods of time in the last couple of years, but not exclusively. He administered 3 mL of 95 percent ethanol to a 600-gallon reef system every day for three days. He stated that within one week, his nitrate and phosphate levels dropped by almost 50 percent and the skimmate produced by the system's skimmers increased and appeared much darker. "Since I measure various parameters on a weekly basis, I only dose with ethanol if the nitrate or phosphate start to climb; I aim for nitrate levels below 5 mg/L and phosphate below 0.05 mg/L," Delbeek adds.

Trying the Vodka Method

If you'd like to try the Vodka Method on your tank and want to know how much 3 mL of 95 percent ethanol per 600 gallons of system water would work out to for your tank:

For a 100 gallon tank that would work out to 3 mL/6 or:

  • .5 mL
  • 10 drops
  • .1 tsp.
  • .0168333 oz.

If you choose to use 80 proof (40 percent alcohol) vodka, the equivalent dosage for a 100-gallon tank would be about:

  • 1.2 mL
  • 24 drops
  • .238 tsp.
  • .04 oz.

That's a pretty small amount. It's important to note that Delbeek administered his 3 mL dose once each day for three days in a row.

Another Experiment

Researcher Heinz Mahler reported that he experimented with the Vodka Method with a 100-gallon tank. He started dosing the tank daily with 3.75 mL of vodka, gradually increasing the dosage to 9 mL per day over a period of six weeks.

Mahler's nitrates fell from 20 ppt (NO3) and 0.2 ppt (PO4) at the beginning of the test to "roughly 0 nitrates, PO4 was with approximately 0.01 ppt" at the end of the sixth week. He then reduced the daily dosage of vodka to 3 mL per day, which held the NO3 and PO4 levels steady.

Mahler noted a fine white powder on all of the surfaces in his tank during the test, but it quickly disappeared at the end of the testing period. He also noted a significant increase in the output of his skimmer during the trial.

From the above 2 experiments, it would appear that the Vodka Method does reduce NO3 and PO4, but results using this method without a skimmer have been inconclusive.