just don't use a spray, and best not even to use a spray in the same room as the tank. Just spritz the wiping cloth with whatever you like, even windex, and clean away: Just don't let any liquid roll down to drip into your sump. Salt is tricky to get off, and you may find a water-wet paper towel followed by a dry paper towel can help.
i use windex, and honestly i spray it directly (lightly) on the glass. Have for years with no ill effects. I do have canopy on tank, so not sure that makes a difference, but my previous tank was open, and i never had an issues with it either.