Excellent for RVs, boats, and portable camping toilets, Walex Citra-Pak Holding Tank Treatment controls unpleasant odors and helps break down waste and RV toilet paper in your RV or marine black water tank. Consistent use helps keep your holding tank sensors working effectively. Easy-to-use portion control prevents messy spills. Just drop it in. One packet treats tanks from 2.5 gallons up to 40 gallons. Citra-Pak contains a refreshing citrus fragrance and is septic system safe, 100% biodegradable, campground friendly, and biocide-free. Comes in a convenient tub with 30 rapid-dissolving water-soluble sachets.• Controls odor up to 7 days• Cleans holding tank and sensors• Breaks down waste and paper• Biocide-free• 100% septic system safe Consistent use helps keep your holding tank sensors working effectively Easy-to-use portion control sachets prevent messy spills Septic system safe, 100% biodegradable, campground friendly, & biocide-free | Walex Citra-Pak RV Marine Holding Tank Treatment, 30-Pack in Black