I've found the best way to control ferret odors is NOT using "products".
It's religiously cleaning the litter boxes twice a day and keeping clean
bedding in the cage.  I totally strip down my cages every two week and
wash all of the bedding and clean the cages.  Others do it more
frequently.  No odor control products needed here.  BTW, I currently
have 9 ferrets in 3 cages.
 
Katharine
[Posted in FML issue 3796]