I've had a small infestation of Hydra in my shrimp tank the most I've seen (and removed) at a time were 10, second most 4. I've been dosing prazi for a little over a week, as I had seen a few people use it and it was on hand. It's not working. I really wanted to try something other than fenbendazole, because of my mystery, nerite, and rabbit snails in the tank. None of the other removal methods really work (introducing a predator, removing and heating, etc), so if there is a better way please let me know. If there is not, how do I keep the snails? I don't have extra cycled media, and I don't currently have an extra tank... How long do I keep them out before introducing them back? How many water changes before then? I really don't want to have to use this, I love my lil snails. Any suggestions are greatly appreciated, thanks!