I use grade A and it worked just fine for me.
I can't stress it enough, this diet may work, but at the expense of your health!! I would never recommend this to anyone. I've heard several cases of girls that have died due to this diet. The saltwater and lack of nutrition triggered heart attacks. They were young too. Granted, they had weak hearts from anorexia beforehand, but how do you know how healthy YOUR heart is? Don't do this diet!!!
Don't forget to do the saltwater flush everyday. It is an extremely important part of the cleanse.