[header] How to get rid of snails in an aquarium [title] Avoid overfeeding. [step] Overfeeding can led to a snail population boom. Try underfeeding your aquarium inhabitants (only feeding enough for the fish to eat at each feeding) to see if that solves snail overpopulation. 
[title] Use a chemical to kill the snails. [step] The most common, fish-safe chemical used to kill snails is copper sulfate.