Maggie, Its me again!!! Check the post on your frog. I used to be a salter and after having other issues with my tanks the folks of fishlore persuaded me that salt isn't that necessary. I have been decreasing
salinity with no adverse affects. Mystery snails do just fine with salt, if that answers your question. Even if they get close to undisloved crystals. I used to just drop it in, then started predisolving it before adding it. Some of the species seem a bit happier without the salt. I did put ALOT of faith in
API products, but don't let that be your reasoning for using salt. I have 2 snails that lived through an ick regimen of high salt content, so no it won't hurt them.