a colema is like a home colonic using whats called a colema board. i actually made my own colema board, but here is a link to what im talking about: http://www.colemaboard.com/
im not an expert when it comes to Liver Cleansing but i think chaff is just like the sandy type stuff that comes out with the stones. i think it floats because ive been seeing some of it float with green little stones, but there is also some sediment type stuff that falls to the bottom of the toilet that i think is chaff too. either way im glad its out of me :) hope that helps and enjoy your week :)