Purchased snails from multiple sources - All were healthy. Some went into 'Tank A', some into 'Tank B'. The snails in Tank A are alive and well today. The snails from Tank B became 'paralyzed' as soon as they went into the tank. They were alive but didn't move much. I would place them against the glass and some would attach and some would not. Those that attached didn't move. What happened here? Water parameters in check, acclimated snails in both tanks the same way.