I have a marbled motoro with a tat, odoe pike, and vatf in a 150 acrylic. i noticed one snail about half the size of a pea a few weeks ago and removed it and now i see about 15. acrylic tanks attract algae quick and they seem to be eating the algae and not on the ray which i am most concerned about. Is there a medication to get rid of the snails or are they ok to keep?