I guess I have the same problem, so I asked. I try vodka for several months, not very good, the vinegar I bought from supermarket has sugar inside, much worth, I can’t find pure vinegar here.so I only try vodka. Maybe every tank is different, the magic just didn’t happen. Maybe it’s about the bacteria. I guess I should try nopox then, maybe it’s better than vodka, as a commercial product, it may contain something different ?as to pure vodka?
Perhaps there are unkown variables that can make it less effective in one system to another but I’m happy I switched back to NoPox as I’m slowly seeing n03 dropping steadily.