[tmz]

Generally, I don't think there is much difference beyond the ability to dose ethanol at one time vs acetic acid which drops pH precipitously in the short term when a large amount is dosed at one time but puts some back in it's journey to acetate . At the end of the processes both acetic acid and ethanol have a similar and equal small lowering effect on pH.

Ethanol( as in vodka) is CH3CH2OH; bacteria( acetobacther /AABs) oxidize it to acetic acid ( aka vinegar/ ethanioc acid CH3CH2OH); just like wine turns to vinegar. The acetic acid goes to acetate including the acetic acid formed by ethanol oxidation.

Some hypothesize that the ethanol oxidizing bateria (AABs) consume a bit more phosphate than when just acetic acid is used but I haven't seen any firm evidence of this. The acetobachter/AABs do ,however, fix nitrogen and may have some additional effect in NO3 reduction, particularly when bolus dosed.

FWIW , I settled on 36 ml of 80proof vodka( equivalent to the carbon from 288ml of 5% acetic acid vinegar) and 60 ml of 5% acetic acid vinegar as a daily maintenance dose for 700gallons and have been in that range for about a decade. PO4 is around .02 to .04 ppm with NO3 around .1ppm in the heavily fed system.