>If the cool air sinks shouldn't you put the bottles on top of the cage so
>the cool air will go down on top of the ferrets?
 
Really a good question.  My reasoning is I want to keep as much of the cool
air in the "box" and don't want the ice to melt too fast.  I figure that if
I keep the ice on the bottom the cold air not going to flow outside the box
on the way down (due to air currents in the room), and the ice, being on the
bottom with the cold air, will cut down on the melting rate a little.  (Of
course the ice does have to melt to cool, but I'd like it to melt relatively
slower.)  The ferrets seem to love to curl up around the ice to sleep, so a
box that's maybe 6 inches deep, depending on the size of your ferrets,
(shallow enough for them to climb in and out), seems to work well.
 
Dick B.
[Posted in FML issue 2373]