MOST IMPORTANT:
Install risers above your septic tank, as seen in my report. Do both the input side of the tank and the output side of the tank. Your tank MUST be serviceable. Then make certain that the output side of the tank has a waste filter installed.
With this work done, you can easily make regular inspections of the water level in your tank, and easily clean the septic filter annually. If you see the water level rising above the outlet pipe, then you know that your leaching lines need to be jetted out. Don't waste money on additives, as the leaching pipes are VERY likely to be packed as seen in my videos.
Get your plumber to dig up your D-BOX and add a riser to make service easy. Then jet out your field lines. The added riser will make future jetting easy. If your property is on a slope, then you have multiple D-Boxes to dig up and add risers to.