I once read that developing film in Diafine bath A for 40-50 minutes produce some thin image. This is very interesting, because this bath contains P+Q in acid solution. So for testing I was replcae Q with C and mix next:
Sodium sulfite 30g
Sodium ascorbate 4g
Sodium metabisulfite 5g
for Neopan SS 100 (expired) I found next development time: EI 100 - 20min, EI 200 - 30min, EI 400 - 50min. all done at 23C and WITHOUT AGITATION! just first 1min initial agitation and leave stand for rest time.
Negatives obtained is very clear and fine grain
PS if you ommit phenidone from formula - you will have blank film. so phenidone is important part