It's not accurate .IME nor in the accounts I've read. It can take months for either to have an effect on high initial nitrate levels.
There are some differences between the two sources(vodka/ethanol and vinegar/acetic acid ) but I don't think they would effect the speed of nitrate or PO4 reduction significantly.
Ethanol is oxidized to acetic acid usually by acetobacteria which are ubiquitous in the air and water ; then the acetic acid from the vodka will convert to acetate at pH over 5.5 as will the acetic acid from the vinegar. Acetate is the organic carbon source for the facultative heterotrophic bacteria that take up nitrogen and phosphate and are heavily exported via skimming. The acetobacteria will also use some nitrogen and phosphate and may also be exprted by skimming .
I don't know about the potential for direct uptake of either ethanol or acetic acid by organisms. Not sure the acetate is directly beneficial to organisms via direct uptake othert han the bacteria that use it but it is likely so,imo. There may also be alternative pathways for ethanol but I haven't found any.
I think,the extra step to get to acetic acid with ethanol slows down the initial H+release that occurs when acetic acid goes into high pH water. It takes some time for the ethanol it to oxidize to acetic acid. This makes it easier to bolus dose vodka vs vinegar which must be dosed slowly preferably during photosynthetic periods Vodka is harder to dose on small systems or via auto dosing given it's relatively high concentration of organic carbon,8 times as much vs vinegar.
There is no proven benefit to using different types of organic carbon sources;the opposite may be true as with sugars for example;in the end it's acetate . No reason to encourage so called bacterial diversity ,imo. The soluble organics primarily vodka and vinegar are closest to the acetate, using them limits the variety of bacteria involved in acetogenisis.
