Snails won't really help keep plants down, plus there a annoying, i have a almost planted tnak or atleast one side is. I prolly have over 20 snails lol, only 3 big ones, but they reproduce and they are pretty ugly to me!!!!! They don't work that well ur probably better at getting a fish that will eat the plants!! U could get snails, but you may end up with too many at one point in time and not wnat them anymore and it will be ahrd to get rid of all of them!!