On my first go around, I siphoned as many as I could from the rocks, sand, and glass, then followed the recommended dosing. For those that remained, I did see them "die", but after a few months I had another noticeable outbreak. This time around I followed the recommended dosage again, but actually saw some that seemed resistant, so I ended upping the dosage to 1.5X which seemed to kill the visible resistant ones. When they showed up the third time, i resorted to finding an alternative solution which ended up being the melanurus, and so far so good as i no longer see them on my glass.