I only take one dose of Epsom Salts 2hrs before oo/juice. Several hours prior to that dose I take 6 capsules Oxypowder . I also use Oxypowder post flush, but at different times to the usually reccomended Epsom Salts . My main aim is to keep the body cleansing, hydrated and comfortable. With this method my flushes have been very successful, with many hundreds of stones each time.
However, I must add that I also prepare well prior to flushing as reccomended by Andreas, and I do go for colonic irrigation the day after flushing, in case there are any stones left behind, which sometimes there are.