I haven't developed my rolls of Delta 400 yet,but, I have found Kodaks' dilution recomendation for photo-flo 200 to be 2x too strong. I use my photo-flo 200 at 1/2 Kodaks' recomendation and get excellent results maximum immersion time is 30 seconds with gentle constant agitation & don't make it foam. I guess the product should be called photo-flo 400 :-). I arrived at this conclusion the hard way with stains and streaking on my negs. I use the old 400 Delta and TMax 100 & 400 with the same staining/streaking problem.(posted 8495 days ago)