When I used to use Photo-Flo I found that half the recommended strength in distilled water worked best. Now I use LFN in distilled water. Be sure to fling all the water droplets and _do not squeegee_.(posted 8543 days ago)Since we can't see these marks, it _could be_ that you're not getting adequate fixing. Agitate it! Kodak used to recommend continuous agitation for rapid fixer; now they've backed off to intermittent, same as Ilford recommends....and many people complain of inadequate fixation of t-grain type films.