We have to do an experiment in my biology class to determine the effect a variable on the hatching of brine shrimp; we can choose any variable we want. My group is going to test the effect of nutrients (mainly nitrogen), and at first we thought we would using plant fertilizer (without any poisons of course). Now I’m considering using ammonia, and I’m wondering if that would be a bad idea because I have to bring it to school. I don’t care about the effect it will have on the eggs because, well, it’s an experiment, and the whole point is to see what happens. It’s not dangerous is it (unless you drink it or something of course)? The odor is pretty localized and won’t spread through the whole room, right?
Well, I don’t care if they die as long as they hatch. 
And the salinity was an obvious variable that a lot of people are doing, so we didn’t want to do that. I also think light would be harder to control. Thanks for the replies!