I ran across this blog years ago. I even linked it to my website. For me, we use plain white rice in the bulk bags. Changing it out as it gets dirty or starts showing yellowing. http://blog.ferretsnorth.org/2011/04/dig-boxes.html One piece of advice, either make the entrance hole on the top or make sure the tube leading in is higher than you rice level. Mine enjoy a longer tub than a deeper tub. I also find that some of mine enjoy the harder beans or even my wood stove pellet clean bin for an extra long scratch. Thanks Kathy of Sammy's Clubhouse Spokane Ferret Rescue and Education Main website: https://sites.google.com/site/sammysclubhouse Like us on Facebook! Adopt your next pet from Petfinder. [Posted in FML 8011]