Every time I've added Photo-Flo to stabilizer, I've ended up with marks and streaks on my film, as if the Photo-Flo simply beads up on the surface of the film. They're easily removed with a damp cloth, but still, it isn't worth the hassle. Don't use Photo-Flo with C-41 film, just the stabilizer. Sirius, PE, et. al., are absolutely right.