Some questions about raising brine shrimp as food? Please help!?

I've kept adult brine shrimp as well as young brine shrimp in all sizes for 4 months in a 7,5 gallon tank. I prepared some salt water using the same kind of salt you use for salt water aquariums. I feed them small amounts of dried yeast dissolved in the water, and I feed them several times a day (whenever the water has cleared after the previous feeding. There's an air stone in the tank which is connected to a small air pump. Apart from that, I don't do more than top up the tank with fresh water whenever an inch or so has evaporated.