The same thought crossed my mind, but the well established theory says that the Epson salt isn't essential to flush stones and it isn't used in all protocols. Also without the purgerative action of the Epson salts the stones may disolve in the gut. On a more practicle note I didn't have any stones on the previous flush either but I don't count the tiny light green ones because at that size they can move around quite easily and they may form normally. I will only be able to find out when I get X-ray vision!