The Retro-Air Rejuvenator System from Septic Services uses the aerobic process to restore failed anaerobic installations or to prevent failures in newly constructed septic systems by delivering a constant flow of air to the diffuser. As the biomat in the absorption field continually builds up, it clogs the pores in the soil, causing effluent water to rise to the ground surface. If allowed to continue, sewage can back up into the home. The system delivers dissolved oxygen and aerobic bacteria in the absorption field. Over time, aerobic bacteria consume the biomat, allowing the soil to absorb effluent once again. It is designed for 500- to 2,000-gallon tanks, and can be installed in single- or multiple-compartment tanks. It includes aerator pod, air line-diffuser assembly, outlet baffle filter and installation manual. 800/536-5564; www.retro-air.com.