I've done 10 flushes now over the last yr and a bit. Sometimes I didn't use the Epsom Salts and got out stones. Also I'd like to mention that the stones are different colors now that I'm onto the 11th. Some are pale brown - not as green as they used to be. My recipe has been consistant in the last 5 flushes so the color should be the same if it was actually the ingredients mixing in my gut and not stones. They are stones, the older ones are harder too, and the fact that I feel so much better after remains unchanged!