[bertoni]

I'm not sure why amino acids would work better for nitrate reduction, since they are a nitrogen source. I agree that the amount of carbon per unit of nitrate is significant, though. Maybe some organism is limited in growth by a missing amino acid. I'd stick with vinegar, ethanol, or bio-pellets for nitrate reduction, at least for a first attempt, but amino acid dosing can be helpful, at least in theory, depending on what's in the food going into the tank. It's interesting that you get good results. Maybe we should encourage others to give it a shot if they're stuck. More puzzles.