TSS stands for Total Suspended Solids. They exist in the septic tank floating in the middle between the sludge on the bottom and the scum on the top. A through septic inspection would include a test for TSS because if the levels are to high, they present a real and present danger to the drain / leach field. The National Association of Wastewater Technicians has discovered that some of the popular products used in septic tanks cause the TSS count to increase. In digesting the solids into smaller particles, the particles are suspended in the middle area of the tank instead of sinking to the bottom. These products add an increased level of bacteria, but because they do not multiply and outcompete the harmful bacteria, they cannot finish the job. The patented probiotic blend in TankTechsRx for Septic Systems is designed to continue to work, completely breaking the solids into clear liquid through the entire system.