[Myka]

For something that small, why not use one of the commercially prepared carbon dosing products? Overdosing vodka when vodka dosing is very easy, and this risk would be substantiated by the small size of your tank.

You will also gain quite a lot if you're dosing bacteria as well as the carbon source. For Zeovit that would involve dosing Zeobak and Start2. Take a peek at the Fauna Marin version as well.