I don't know who started the idea of slow agitation with hangers but this is the cause of surge marks at the holes. It has caused me a bunch of ruined 8x10 film. It doesn't have to be that way. I'd like to pass this on so anyone wanting to use hangers can avoid this dreaded problem. You must agitate quickly ie, out of the tank in 1 second, tip to 45 degrees, in the tank in one second. Next repeat the same sequence only tip to the opposite side. This should take about 10 seconds for the 2 pull outs to be completed. Apply this to you're initial and periodic agitation schemes. An additional tip to dislodge bubbles... After initial agitation when returning film to tank, drop them in from about 2 or 3 inches above. That's it! No more surge marks. I hope this saves some a few headaches.