MTS quickly over-ran my tanks when I first introduced them--but, just as generally happens with pond snails--the population is beginning to stabalize with a bit of help.
I've two assassin snails in my 37g (though they mostly go after the pond and rams first, I have seen them eat MTS) which nibble around the edges and I've got several means of removing the smaller snails:
--swipe the glass walls early am or late pm to gather up ones that have climbed the glass (easy to knock 'em loose from plants and catch 'em in the net as they fall as well)
--bait and lift with fresh veggies (always a pain to sort out the rams and ponds I want to keep, though)
--wait til most of 'em are out on the open sandy areas of the tank in the pm and use a open-weave net to scoop up and sift them out of the sand. Larger snails are returned to the tank, tiny to mid sized are dumped.
Just as with my pond snails, I've noticed the reproduction rate is dropping and I'm seeing fewer bursts of new hatched babies as the population gradually shifts towards more large adults. Hasn't been long enough to know if MTS follow the same pattern as ponds, bladders and rams--but the largest adults of those species show a tendency to have slower rates of reproduction than young adults.