I do alum. 3 tablespoons per gallon, soak new plants for 2-3 hours, then inspect and rinse well. Can’t swear it’s 100% effective, but I don’t have any pest snails so far.
Edit: this method is for introducing new plants, as is the bleach bath, usually. Probably won’t work if they’re established in a tank, as they’ll be in the substrate, etc.