Nope, make sure you use stress coat for saltwater... I hear freshwater stresscoat will foam up in your tank or make your skimmer go crazy...can't remember exactly.
The only conditioner I have ever used for saltwater during water changes is prime and that's because I use tap water. If you are using ro water like pufferpunk said, you don't need any conditioners.
I only do one everyonce in a while. I don't buy into the idea of water that is being constantly filtered getting old, hey but what do I know. I do dose every now and again.