Reducing Nitrates in Your Marine Aquarium With the Vodka Method

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Is it really possible that by 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.

In the Q & A section of the September 2010 issue of "Aquarium Fish International 404" magazine, Charles Delbeek, MS (currently a marine biologist at the Steinhart Aquarium in San Fransisco, CA) 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% ethanol to a 600-gallon reef system each day for three days. He stated that within one week, his nitrate and phosphate levels dropped by almost 50% 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 (NO3) levels below 5 mg/L and phosphate (PO4) below 0.05 mg/L," Delbeek adds.

Trying the Vodka Method

For those of you who might want to try the "Vodka Method" on your tank and want to know how much 3 ml. of 95% 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.

For those of you who choose to use 80 proof (40% 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. Don't forget that Delbeek administered his 3 ml. dose once each day for three days in a row.

Another Experiment

Heinz Malher, on the Reef Dreams website, 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 6 weeks.

Heinz's nitrates fell from "20 ppt" nitrate (NO3) and "0.2 ppt" phosphate (PO4) at the beginning of the test to "roughly ZERO nitrates, PO4 was with approx. 0.01ppt" at the end of the 6th week of the test. He then reduced the daily dosage of vodka to 3 ml. per day, which held the NO3 and PO4 levels steady.

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

From the above 2 experiments, it would appear that the "Vodka Method" does reduce NO3 and PO4. We haven't been able to find any test results from using this method without a skimmer.