RV Digest-It Classic Holding Tank Treatment Treats Black and Gray Tanks 32 fl oz 16 Treatments - 413 This concentrated black tank treatment uses a proprietary blend of bacteria and enzymes to maintain already clean working sensors eliminate odors and liquefy the solids in your tank leaving you with nothing but great camping memories. RV Digest-It is the most trusted and widely used combination treatment eliminating tank odors AND breaking down solid waste ensuring no clogs and no backups. *Ingredient disclosures are to the best of our knowledge based upon information provided by our raw material suppliers.