A septic tank doesn't need pumped all that often and you can use Ridx to help keep the good bacteria inside the septic tank to break down the solid waste to allow more time in between septic tank pumping.
Most septic tanks only need pumped every 3 to 5 years but sometimes can go longer for up to every 10 years before needing pumped.
But expect to pump the septic tank at least every 5 years to keep the septic tank clean and prevent backups of sewage into your home.