Welcome back... I've been on the Master-Cleanse at the same time as you in the past. My sister and I both have a terrible time with fluid retention, and have found the Epsom Salt bath to help. I haven't done it for a while, so I can't remember the quantity. I remember someone on one of the forums warned that one should never be alone and shouldn't stay in the water more than 20 minutes.
My grandmother swears by grapefruit juice as her diuretic, but it doesn't work that way for me at all. Everyone's different.....