I will look into trying the larger volumes, but given the cost of the soup I prefer to use as little as possible.
One reason I do not think it is related to the amount of solution used is that when I made an 8x10 cut from the 16x20 paper and an 8x10 from a different pack (using the correct filtration for each) the new paper still exhibited the magenta cast. The first sheet i cut up did not have this cast in any test i used it. I wish I still had a piece of the first sheet I cut up so I could do a more dirrect comparison. So it looks to me like not all the paper in the pack is the same emulsion. I will pull a sheet from the bottom and test it as well.