If the material is black or green then you can be sure its plaque....I kinda had this same problem when I did colosan...The first week i was passing black water then i went back to brown....The best thing to do to keep passing plaque is make sure that you take your colosan dose at least 1 hour before a meal and no less than 2 hours after a meal...This will allow the powder to lock on to old material instead of the meals your eating that day...I know colosan and oxypowder are similiar...Colosan was dead effective and eliminating worms, parasites, flukes etc...But not nearly as effective at eliminating plaque...I suggest if you want to get rid of tons of plaque do p and b shakes with bowel herbs...If you want the protocol I use let me know and ill give it to you...It will make you pass tons of plaque...