I use 1 ml per 25 gals as instructed and it works great. Nitrates = 0
I have about 175 gals, so I dose 7 ml per day.
I have been using for about six months and I am on my second 1 liter bottle. I use my old API test vials and caps to make up two weeks of daily doses and just dump one in my basement sump each night when I check the system.