I found a source for KNO3 as I was not sure which stump remover to buy that was pure. The company is ECO Enrepriises 1240 NE 175th Street, Suite B Shoreline, WA 98155 1-800-426-6937 I oredered what I think is 1 lb# of pure KNO3 for $5.98 and should last me for at least 10 years! :-) With the shipping it came to $11.20.