It is a good thing, what floats is fat (reason the stones float). When your feces were floating it was a sign of fats not being digested properly cause of not enough bile.
Make sure your diet is of fruits and vegetables, seeds, essential fats, full grains and avoid processed crap, dairy and meat. Make sure you excercise and sweat at least 30 mins a day and try some herbs for your kidneys too. Your skin will improve.
I have passed many stones and yea and some of them were big and bright green but that has not always been the case. You will flush whats next. The last stones I passed were dark green and not that big.
Juat man up. If you could drink the first 3 you can do the 4th. Drink it fast and rinse your mouth. I have read protocols where they do not even take any Epsom Salts but the salt is to help flush the stones and to make sure your bile ducts are relaxed.