yellow rabbit snail help

[tyger_eyes]

i have two of these awesome looking guys in a 55 gallon with some tetra, cories, and kribs. the tank has driftwood which may make the water a little softer, the pH is at about 7.4-7.6. i put a weekend feeder block in the tank to boost calcium in the water. i was checking on the tank and i swear one of the snails was dead. it looked shriveled up with sand in it, so i put the net in to scoop it out and it moved. then it buried itself. i can't say for sure but it looks like they may have pin sized holes in their shells and i cannot remember if that is how they always looked.
i have another tank with the same pH but no driftwood, it has platies, guppies, and cories in it. i was wondering if i should move them into that tank and add something to boost the pH like corals or something. i need to know if this will hurt the existing fish and be able to save the snails in time. any help is appreciated.
both tanks are cycled, i checked all levels before posting and the only thing of interest is a slight nitrite level in the tank with the snails (.25)
i can't get any pictures because my camera sucks. i used pH instead of hardness because i don't have a hardness tester, used it all up.

[tyger_eyes]

update:
found a stick type hardness tester and best i can tell the 55 gallon with the snails is at about 75 GH and the other tank is at about 150 GH. the snails are still moving around but i don't like the looks of their shells, parts of them look worn and there are pin sized holes. if i move them now will i be able to save them? should i move them at all?

[Death Pony]

Their native waters are actually fairly soft with a high pH. I've seen plenty with pin sized holes in the shells. They take breaks quite frequently.