How can I kill the worms in my snail tank without killing the snails?

I have a 10 gal. tank that I use to breed pondsnails to feed my two puffers. Today I noticed these tiny white worms in my snail tank. I know where they came from, my question is- how can I get rid of these worms, without killing my snails?|||Take out all of ur snails out of the tank and throw out ur old substrate and put new ones|||Replace your snail tank.