I have been working up to a time/temp combination with Pyrocat HD and 4x5 FP4 for stand/semi-stand. I have arrived at a good contrast level (for my Aristo V54, Dupont MG filters, and Forte Fiber VC paper. ASA 50 for the film (final test negs shot with incident readings to eliminate any "previsualization" errors. I use hangers (someone on a thread once said hangers are ideal for stand development). The tanks hold about 2400ml, the reason for the measurement. Agitation is alternate diagonal draining off of each corner, continuous, being careful not to be too turbulent about it, but to keep things moving (learned about surge marks many years ago in the Army). 73F, 15:10:2400 with distilled water (very close to 1.5:1:250). 2 minutes presoak (mostly continuous agitation, tapping off airbells now and then), into the developer - 1.75 minutes initial continuous agitation, 30minutes development, agitation for 15 sec (4 lift and drain, 2 on each side) at the 10 minute marks. So, they get 2 agitations, one at 10 and one at 20 minutes. When I was doing individual sheets to establish time/temp, I didn't see any problems, but what you can see in the attached images came from the last development session, these 2 negs are from a group of 4 films done together. The tanks are good size, have light tight lids (the ends of the hangers sit on a "shelf", an inch or so below the top of the tank), and are great for doing this, and hold 8 hangers. The top surface of the developer is a good 1/2" or so above the tops of the holding bales in the hangers. You can see that the offending areas are related to the hangers, surge of some kind, I guess. Image one is along the left side, and a dark vertical edge running down the large butress. Image 2 is along the right edge, with a dark area somewhat along the top on the right side (hard to see in the attachment). Both hangers were positioned the same, in parallel, so the problems are opposing, in a sense. I am disapointed at getting so close and have this problem. The quality of acutance is just what I want, so I'm inclined not to agitate more often...but will if I have to. Sorry for the long post, but I wanted to be thorough. Any suggestions?