Hi Joe, Oh yeah, it's C. A lot of what I used to get was what the GI called false D, the liquid slips by the C. Fiber has pretty much eliminated it for me but if I go low on fiber, I get backed up and start with the little pellets. I really did have real D too which was caused by fruit, etc. My C stools don't necessarily tend to be darker, it just depends, they vary in color as much as always. If you're upping your fiber to help this, do it very slowly. Jackie