The minimum temperature for Diafine is 21C. And the regular developing time 3+3 minutes. Some films, Acros 100: 5+5 minutes.
Good Diafine combinations: Tri-X 400 (E.I. 1250), HP5+ (E.I. 800), Neopan 400 (E.I. 640), APX 100/Rollei Retro 100 (E.I. 200). Acros 100 (E.I. 160).