[lenaitch]

There is a lot of debate for and against adding yeast, but for the price of it, why not if it makes you feel better. I do think 20 years is a little long. Best to get it pumped and inspected. The inspection report will give you a good baseline of your use and confirm the tank and visible internal bits are in good shape.
As mentioned, once solids enter the leech field it gets pricey. I let ours go too long at one place and the solids floating on top were so dense the tech could stand his shovel in it. New effluent going into that tank had to filter through that mess. One big thing many people forget is to not put harsh chemicals, such as bleach, cleaners, etc, into the system as they kill the bacteria and grease just clogs things up.

We get ours done every five years (2 adults) which is a little ahead of the curve as our township requires every 7 seven years.

 

[lenaitch]

It's like an old farmer 'joke' my dad told me years ago, that they would toss a dead chicken into the tank. 'Why a dead chicken?' Because the live ones put up too much of a fight. Bada boom.

 

[lenaitch]

Throw in a live chicken? Wasteful beyond the point of being sinful.

How often to pump a septic tank is trial and error although you can take an educated guess such as the 3 years mentioned previously. A good pumping technician can improve on the educated guess after the second pumping.

Since you don't know the amount of solid matter in the septic tank when you buy, close, and move into, a non-new house it is a good idea to have the septic tank pumped immediately unless you know for a fact it was pumped within the past year,.

Pumping a septic tank again in quick succession does nothing more than cost money unless you need to inspect/repair the interior or you need to convert it into a holding tank termporarily (no structural changes or additions needed for this) while the leach field is serviced or rebuilt.

The key word was "joke".

 

[lenaitch]

Not sure how common they are but you can have a effluent filter added to a septic tank. It is a plastic baffle that prevents solids from entering the drain field.
They can clog and may need periodic rinsing (garden hose spray), but at least in theory it should save a drain field. It's has been 6 months since I had one installed and yet to need rinsing.

https://www.thenaturalhome.com/septicfilter/
this link is a sales pitch, but if you look at the schematics near the bottom you quickly see how it works

A friend has one on his system; cleaning it is his least favourite job. He has a neighbour he doesn't like and tries to time it for when the wind is blowing that way.