Since not everyone can get assissin snails, you can always cut a carrot full length put the lengths in the tank over night. The next morning the snails will be swarming all over the carrot. Lift the slice of carrot out holding a net underneath to catch any snails that release and try to escape. Then you can easily scrap the snails off the carrot (and put it back in the tank for another go at attracting more snails), and the snails that are now out of your tank you can throw on your garden (if you by doing so there is no chance the snails could make their way to a local waterway - maybe better burying the snails in the garden), if you have a composter bin put the snails in that, if you have fish you can crush the snails and feed them to the fish, its amazing how many fish love eating snails that have been squished for them.
