There are a number of ways to make green water... Do a web search if you like.
This is how I culture my green water:
Add old aquarium water, along with some dead plant matter or detritus to a glass quart jar or similar container.Fill the container about 3/4 full. Allow this container to sit in a windowsill for a few days catching some sunshine. In a few days it should be cloudy and/or green tinted. It is then ready to harvest and should have very little smell. But, if you are curious enough to stick your nose where it really doesn't belong you will be duly rewarded.
You can either harvest an ounce or two from the top, with an eye dropper or for larger amounts/container a turkey baster taking care to not get any of the mulm or solid material. Squirt this tastiness directly into the tank containing the larvae.
In a 10 gallon tank, 2 oz or so per day of the culture should keep the larvae fed until they molt and mature into miniature adults. If doing lower numbers, simply keeping an unkept aquarium with lots of dead plant pieces, detritus etc on the bottom will support the larvae. However, most aquarium keepers don't like the way aquariums look when kept this way... If you keep several jars going, you will have a constant mature source of culture to feed your larvae.
Capturing and sorting grass shrimp larvae would be a trick! But adult grass shrimp are and will be in high demand and could easily carry a 25-40 cent per shrimp price.
