How to treat snail infested aquarium?

put some lettuce on the bottom of the tank (you may need to anchor it down) before you go to bed, then when you wake up pick out the lettuce and all the snails on it. That method is used to lower the amount of snail, but I don't think to eliminate them. If there's no fish and just snails, why don't you just clear out the water and clean out the tank and pick off all the snails. You can do as many things of lettuce as you want if you don't want to clean out the tank. And I don't think you need to do it at night necessarily, I would think you can do it when ever you want, just don't let it sit too long, because they'll eat it and multiply more.