My experience is that they do well from 1.003 to full marine. Pick a salinity that fits your intended tank mates. If only the scats, stay on the low end to save on salt. My tanks have always hovered around 1.005 and have always had (happy) scats.
Understock, overfilter, and adequate but judicious feeding are the keys to a happy tank. Right now, the best you can hpope for is 2 of 3. Make them count!