Reframer, salt is not good for snails, low ph is not good for snails. far as i know, water softeners cause low ph. you are supplementing with calcium to combat shell erosion? maybe find a source of water that is not softened, maybe the tap on the outside of your house instead of the faucet on any sink inside your house.
Moesmom, whatever amount of snails you estimate will come out of a single clutch, times that by at least two, and that will most likely be the number that actually hatch out, lol, trust me, this i know!