It DOES happen at the end of the 3 day closing cycle. That is exactly what makes so many people report feeling miserable in between rounds but great while on them. That is also why Dr. Cutler recommends taking DMSA or oral DMPS along with the ALA, because they have a stronger bond to mercury and can "mop up" what ALA leaves behind. It is also why some people recommend taking the DMSA or DMPS for a day or more after ceasing the ALA.