Waltergoose

Mine is growing very slowly in a tank with guppies/cherry shrimp. Current parameters are ph: 8.0, TDS: 250-300, gH: 12°, kH: 3°, no CO2. It does not tolerate glutaraldehyde (liquid carbon) at all.

There's no telling exactly how long it will take to get the fenbendazole out of the tank but using an activated charcoal filter should help remove it on top of large water changes. Unfortunately this paper I found (Here) suggests fenbendazole is pretty insoluble in water, meaning much of it will likely stay in the substrate unless you can remove it somehow, and it doesn't degrade noticeably in a 30 day period unless exposed to sunlight. Hope that helps with your decision.

Can't really pass that up then, I'll take a pack.

Are these all small varieties?