its been a hwile since ive set up a salt tank, actually about 10 years i think, my recommendations would be to do some research to determine the conditions in which brine shrimp breed in the wild, then get a refractometer or something along those lines to measure your salinity and add salt accordingly. just remeber when replacing water from evaporation you do not need to add salt, because the salt is still in the tank, only during waterchanges where your physically taking water out of the tank do you need to add salt.