The majority of us know at least one fellow reefer who swears by dosing his/her reef aquarium with vodka. This seemingly counterintuitive act is often believed to have beneficial effects on the overall health and appearance of one’s reef aquarium. But how is this possible? Why vodka?Vodka differs in composition from other spirits such as gin and whiskey. Vodka is composed almost purely of ethanol and water, while other spirits are composed of ethanol, water, and potentially non-reef-friendly ingredients that are used to enhance flavor. Now that we understand why vodka is the spirit of choice, let’s discuss how ethanol – its “active ingredient” is believed to assist our beloved reef aquariums. The addition of carbon-rich ethanol is widely believed to promote an increase in bacterial biomass. This increase in bacterial biomass results in the uptake of phosphates and nitrates from the aquarium’s water, yielding benefits that we are all too familiar with. The aforementioned increase in bacterial biomass necessitates the use of a protein skimmer, which may remove some of the bacteria and its byproducts. Many aquarists gauge the success of their vodka dosing by observing an increase in the output of their protein skimmer.