There was a time when my pond was koi~less and
the snails got out of hand. You'd walk on the bottom
and they'd go crunch, crunch. I worried about the pump
and plumbing. I put in a couple hit koi and the problem went away.
I've seen land snails venture out into the pond on
lily pads and the koi circle underneath like spotted
sharks. The snail would look over the edge and
that would be the last thing he did!
My pond is a critter pond, and all critters, within
limits, are welcome.

k :-)