I've always heard that the best way to control their population is to put some cucumber slices on the substrate just prior to lights out. The MTS will flock to the cucumber to eat. You can simply use this "trap" to remove as many as you want.
You could even put a dwarf puffer fish or loach in. They'll eat snails.
When you pop the lights back on a couple hours after lights out and they are coating everything in your tank, including the glass. If they get out of control catch them at night, pluck out as many as you can. Mine like to crawl on the glass so I run a net from the bottom of the pane up. Hand pick the big ones, since they will be your main breeders.