I have had good luck with the 1 time I have used it. Follow the directions on the box to the "T". Try your best to remove as many as you can see before you treat the tank to help decrease the potential effects of the toxin that are released when the little buggers die. Have your water change mixed and ready along with GAC. Good luck!
+1 It works fine as long as you follow the directions. Seconds after dosing they begin to writhe and die.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. - George Bernard Shaw