Pond snails

Quick question:
  I have small snails in my tank.  The pet store said they
were "pond" snails.  WOW! the waste they create is
unbelievable.  I need to feed them 'Immodium', :-)  No,
seriously, I have been vacuuming the gravel and picking them
out.  Is this the best way to get rid of them and will I be able
to get rid of them?  I know I can't use copper based products
because it will harm the plants.  What about changing the
pH, temp. or hardness to affect the snails.
Thanks for any help.
Paul L.
Knee deep in IT!