I hate that you're having to deal with an outbreak of anything, but I'm with you on suspecting ich. I know it's not the only thing that causes white dots, but it's definitely the most common. I've never tried my hand at salt water, but at least on the fresh water side API Ich Cure has has been my go to for a few years. I hope that it's just ich because in my experience it's been relatively easy to treat. Regardless, good luck and keep us posted!