You absolutely can not use table salt. It can not be iodized. If possible, seek out organic sea salt (although I admit that's a bit of a misnomer if there ever was one). But the meaning of the marketing term is simply neither iodized nor refined. Sea salt works for me every time... If you scooped a bucket of sea water, evaporated the liquid, and had 2 teaspoons of salt left or your sea salt cleanse, you're off and running (to the bathroom ;)
If that is unavailable, get any other non-iodized salt like himalayan salt because it's from an ancient sea.
NOTE: Don't believe the hype that salt is the devil (although as is the case with most of our modern conventions, industrialized, refined table salt is indeed the devil along with white sugar and white flour. Salt is an essential nutrient. We come from salt water. Saline is in our existence. Did you know our saliva is 99% saline? (the name kind of gives it away) We need it. We just need it in a natural form.
Sea salt, natural un-refined is needed for your salt water cleanse because it takes up the same "specific gravity" of your blood, and is therefor not digested, but rather passed through the body, eliminating quickly, and flushing through your pipes on the way. A perfect example of a health hack if there ever was one.