I'm not an expert on snails, but I know a little about water. I wonder if you have a water softener? Salt kills snails. When I buy aquarium plants I dip them in salt water to kill the snails. They tend to multiply worse than rabbits.

no, I don't have a water softener. There might have been a tiny bit of salt in the water though. They convinced me at the pet store that a little salt for fish stress would be good but I have only added half the recommended amount maybe 2x with all the water changes I have done in the past almost 2 months that the tank has been set up.

But I still don't understand how this area has problems with the snails. Or maybe she didn't know what she waas talking about.

Copper will kill Inverts even faster than salt, but before you buy any more snails, regardless of what a pet store employee told you, test your water before and after ageing and/or conditioning with chemicals, to be sure.

However, if you have been adding salt with every water change, that could be the problem. Unless any aquatic animal, fish or Invert is native to salt or brackish water, salt is not a natural conditioner- it's a killer.