gallon of warm water, mix in a good handful of aquarium salt and use a air stone to bubble and agitate the water for so many hours. they've hatched when the shells tend to float to the top when you turn off the bubbles. if you shine a flashlight threw the water you should be able to see movement of them swimming.
for me at least I would turn the bubbler off, let the shells float to the top for a few min and then siphon the water/shrimp out leaving the shells behind. then using a brine shrimp net drain off the salt water and give them a quick rinse. into the fry tank they went.