If it's just light cutting, I've run it dry, or sometimes I'll drip a little tank water on the blade.
If it's some serious fragging and cleaning up rocks off of colonies, I'll put tank water in the basin.
Salt water and power tools... I was a little nervous at first, but when I didn't fry myself, I figured I was ok
YMMV
You could throw one of the Stanley GFCI's on your saw. They are total crap for reefs because e-ballasts can fool them and make them trip. But super touchy GFCI is probably just what you want on a wetsaw
Oh yah, rinse well afterwards.