The Koralia's definitely have power cords, I have two #2's and love them.Electric45;3649604; said:i havent bought it yet but ive just looked at some pictures and didnt see a chord for the koralia powerhead.
I would buy a refractometer for salinity, I got mine from Dr. Fosters reasonably priced http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=9957. I feel they're a bit more accurate. I wouldn't want to wonder about something that important.
You seem well researched/planned and that's a huge + when doing SW, best of luck, let us know your progress!