Just as an experiment I set up a tiny plastic planted tank (6" x 2.5" x 2") with a java moss rock and a tiny crypto. I stocked it with a few snails from my big tank and used a tiny dossage of excel to make the java moss grow faster. In a few hours 1 snail was floating dead at the topof the water and the other three were crawling above the water line. so is it possible to kill snails with an excel overdose?