I have to comment on a couple of other replies, though:
1) chemical treatment of snails most often involves copper (check label). That harms all invertebrates as well as many catfish and scaleless fish. I would stay away from it.
2) Blue Gouramis do not eat snails.
was just going to post that blue gouramis do not eat snails
the best thing i've found is avoid overfeeding snails reproduce more if theres an abudance of food and the best way is to put a plate with algae wafers at night and every morn take the snails out do this for a week and it will get rid of most of them it may take a couple months before it needs to be done again
has this worked for you i tryed it on a 10 gal and it did squat the snails buried them selfs in the substrate when i changed the water a month later they came back
i added a table spoon per gallon i had removed the fish to try this.