I would strongly advise against dosing of vodka to your tank directly. If you want to dose vodka, only do so in a denitrator unit.
If you dose it directly into your tank directly, the heterotrophic bacteria will outcompete your true nitrifying bacteria and your nitrifying efficiency will be greatly reduced. This will be dangerous considering your bioload.
http://www.biofilters.com/webfilt.htm
"In general, there are three types of aerobic microorganisms that colonize biofilters for aquaculture. Heterotrophic bacteria utilize the dissolved carbonaceous material as their food source. Nitrosomonos sp. bacteria utilize ammonia as a food source and produce nitrite as a waste product. Nitrospira sp. utilize nitrite as a food source and produce nitrates as a waste product. Nitrosomonos and Nitrospira will both grow and colonize the biofilter as long as there is a food source available. Unfortunately, both of these types of bacteria are relatively slow growing. Heterotrophic bacteria grow about 5 times faster and will out compete the other two types for space if food is available"
http://www.bioconlabs.com/autoheterobac.html