It is how much nitrate 1mL of the solution adds to your tank. A 3 or 4mL dose of the 250mL mix is a good start (10-15ppm NO3). Some like to dilute their mixes so it is an easier dose (teaspoon ~ 5mL).or is this "nitrate level" what the estiamted level would be if i poured say, a cap full every day?
Grants stump remover takes longer to dissolve than the KNO3 Greg sells. The powder takes longer than sugar. I dry dose most ferts and my fish and shrimp have been okay. Dissolving it first is safest especially if you think your fish will keep eating it.
HTH