Your town may have specific requirements. At the very least we recommend a scheduled inspection based on use and pump and repair the septic system as needed. No, there is no scientific proof that shows septic system additives help your system to function better, and they may harm the system in the long run. Save your money for inspections and pumping. I ve had my septic system for 20 years and never had to do anything to it.
Every system needs pumping eventually.
If your system has never been pumped then the solids are going somewhere, either direct discharge to a water body, groundwater, or into the drainfield. Basically the system includes an additional component such as a sand filter. Each component plays a different role in treating the effluent. One component may reduce waste strength or remove pathogens, while another may remove nitrate-nitrogen, others, working in combination, do all three. The type of advanced treatment system that you install will depend upon the water resource you are interested in protecting.