When will they die!?

[Aqua sobriquet]

I dosed my 35L Nano with Fenbendazole today to get rid of planaria and six hours later they're still alive. With no fish or shrimp in the tank I used double dose .2g as well! So how long till it works folks!? :?

 

[Aqua sobriquet]

24 hours later, no change. I've added another .1g