I use reptile powdered calcium <em>WITHOUT</em> any added vitamin D. I've also used tums, but I wanted to do something a little more pure (I wasn't sure how good the flavoring was for the snails.)
For baby food, I think the squash flavor and green bean flavors are the highest in calcium. And yes, a jar - or a cup, since Gerber has gone away from the glass jars.
I always wing it when making snail jello...and haven't gotten the gelatin ratio right just yet. I either end up with snail jello that dissolves too quickly or becomes snail jerky and they won't eat it.
I personally would try sticking an air stone under the egg sack, the bubbles popping on the surface is usually enough to keep them nice and moist. Though I've only hatched one batch like this, and was not interested in hatching multiple. And also I didn't have to place an air stone under the egg sack...
The egg sack was laid at the output of my filter, which is an air/sponge filter. Amazon link. That black circle at the top is an air exit, and air bubbles are constantly pouring out of it. I just angled that towards the egg clutch, and next thing I knew I had babies in my tank.
In theory, this should work with a simple airstone being placed under the egg sack, but the air bubbles would be less concentrated so I'd keep an eye on it. I may have gotten lucky with a 100% hands-free hatch lol.
I bought mine from here:
They ended up sending two instead of one. One was black the other was brown striped. They were packaged perfectly and have been doing great for over a month now. They actually shipped out about two days after I placed my order and arrived within two days after shipped.