The "green water" algae you need to grow for feeding to brine shrimp has to grow in brine, doesn't it? If you just add salt to freshwater "green water" don't you kill the algae? (I'm a newbie at brine shrimp growing-out, you can tell.)
But at www.brineshrimpdirect.com they suggest minute amounts of dried yeast, or powdered spirulina from the health food store. You'd have to shake it up with a little water first. The trick apparently is not to foul the water and kill the Artemia...