Quote Originally Posted by MattKing View Post
I was thinking more of a 500 ml bottle of Ilfostop concentrate or Kodak Indicator Stop.

In other words, a mixing mistake.
Yeah I just figured who would pour a 500ml bottle of KIS into anything given that the ratio is 1:64 and they're probably not making 32L of stop. ;-) Additionally small tanks are 500ml so I can see how the gears probably would have turned.