If you search acetate use for increasing bacterial populations to reduce nitrate, you will find that it is quite effect for this purpose in both aerobic and anaerobic environments. Much of the research is completed using waste water (fresh water), but there is a lot regarding marine water. Vinegar brakes down quickly into acetate. I have not seen research completed using ethanol. Most is completed using methanol since it is cheaper. Methanol works fine for aerobic purposes. In freshwater anaerobic environments alcohol seems to inhibit many bacteria from growing, at least in one paper I read, which I can't find again.
If alcohol inhibits saltwater anaerobic bacterial growth as is suggested in the article noted above performed in freshwater, then this may account for why cyanobacteria are more of a problem while using vodka.
Keep in mind, that when bacteria masses form biofilms, these biofilms contain both aerobic and anaerobic bacteria which work together to reduce nitrate & phosphate in a reef aquarium. Studies on how bacterial biofilms work is enlightening in that it does not take much of a biofilm to retain anaerobic bacteria. Given this information, I would expect that all sand beds shallow or deep contain lots of anaerobic bacteria as well as live rock.
FWIW, anaerobic bacteria are in general more effective at reducing the nitrate and phosphate IMHO. This is why that I speculated cyano bacteria form on live rock and sand beds, since without dosing a carbon source, the sand beds and live rock don't seem to handle much of a nitrate and phosphate load.
Studies have shown that sand beds will add to the nitrate in aquariums without adding carbon sources. Once you add carbon sources to the sand beds, then they can keep up with the nitrate load, especially in tanks with lots of fish. The solid carbon polymers recently arrived on the scene, seem to do a good job in sand beds as well as vinegar according to the research.
