Hi there,
I haven't used Oxypowder but I am using Mag O7 which is supposed to be similar (& more affordable).
It's amazing ! - it just does what it says: make stool soft loose and easy to push out of the system :). It is like the kind of stool you get after using a simple home enema. Like you I have done juice fasts before but this time the oxygen powder made allt he difference :). Hope this helps :)