Let me ask you this. Our septic is 3 years old. It’s supposed to be a raised bed system we had put in. In August, we had it inspected because we are selling the home. The septic was full on both sides. It was pumped out. My gut is telling me this is full again. What would be causing it to fill so soon? There are only 2 of us in the house. Septic was put in brand new 3 years ago. Does this mean leach field is not work correctly? And, in your experience was something not installed correctly to be having these kinds of problems already on a new system?
Most septic systems have a distribution box which drains into a leach field. Either or both may be clogged and not allowing water to drain out properly. Or if you live in a really cold area, the water from the leach lines could freeze and block drainage. Have a septic company come out and check your leach lines and distribution box. It’s kind of late now, but you should be using a product like RID-X to keep friendly bacteria working to decompose the solid waste.
Also, consider that the septic drainage issue is not likely related to the product or system you are using, but the manner in which it was installed. It might be advisable, since you are selling the home, to have a septic tank expert to come out to your home and provide you with a full inspection as well as action plan on how to address this issue. While it is not clear how soon your two tanks re-filled, I agree that if the time was only a few months then you have a clear breach in how the sceptic system as a whole is suppose to operate. Hence, the most likely cause lies in the distribution flow and so issues such as obstruction, the material used, and the slope of the lines should all be given careful scrutiny.