Roughly 2/5 of the package, and after I put it in the tea bag i shook it around the tank a little, because of the fact that my sponge filter doesn’t produce much flow. Following the shaking, I tied it to the sponge filter and left it for about 5 hours. I watched the planaria squirm and die, however I noticed the planaria again about 1-2 weeks later. Sent from my iPhone using Tapatalk