I have those snails too in my nursery tank i put outside. Cleared up algae really good. Though I don't like them for doing that, the algae was supposed to be for my mollies and their offspring. My father keeps a rather large flower horn so I catch a bunch of snails with a net (snails are too gross for me to pick up with bare hands) and i feed them to the flower horn. Free live food supply . And they seem quite harmless to plants, i've a bunch of elodea and vallis in tha tank and they don't seem to be very much bothered by the snails.