I have experienced the same problem. No problems with Ilford or Kodak fixers, major problem with white residue when using TF-4. Worse, it was causing scatches on the backs of my Tri-X negatives. I had just switched back to Kodafix, but now that I know someone else is having a similar problem, I will call PhotoFormulary and try I little more experimentation to see if I can find and eliminate the cause.