CRUSHED OYSTERSHEEEEEEEEELLS...
(http://www.hermitcrabpatch.com/Oyster-Shell-Calcium-Supplement-Small-p/su001.htm)
I sprinkled some in my 10 gallon tank, and I see the snails flock to it from time to time.
Not so much with the shrimp, but I guess whatever dissolves in the water, ends up helping them in the long run.
I've also heard that TUMS works for building snail shell growth, but I'm still iffy about using tums
;
As for feeding shrimp with something with calcium sulfate, it should be okay, as Cory had mentioned. You don't haaaaaave to feed them per se, because they're fine with just the biofilm that grows everywhere in the tank.
I tend to feed my shrimp tank once a week with repashy shrimp souffle that Cory sells at his store. Just made a small batch, and froze the rest.
It's great for weekend food, because the gel stays "fresh" for up to 24 hours, and it doesn't cloud the water. Granted, I put such small amounts in my tank, my shrimp end up eating it all within hours. LOL...