By "capacity" do you mean minimum chemistry required for developing per tank?
If so here is what I found, and follow for my E-6, B/W and (if I can get the chemistry) C-41.
Chemical volume for JOBO system 1500 tanks.
Chemical volume for JOBO system 2500 tanks

In my 1520 tank I use 240ml of developer for two rolls of 120 or 135. When I use the 2523 tank I use 270 ml of developer (rotational-mode for both).