jackson wrote:

The baffles help prevent the solids from the
tank entering the field.

The baffles are there primarily to prevent the floating scum from
entering the leach field.

A septic tank separates the incoming sewage into three layers:

- scum (floating on top; consisting mainly of grease, soap, hair, and
lint)

- sludge ("solids", on the bottom, mostly poop that hasn't decomposed
completely yet)

- liquid (the middle layer)

When operating properly, only the liquid flows out the septic tank and
into the leach field, where bacteria in the soil break down the
pathogenic bateria in the liquid.

If the floating scum layer gets too deep, it will get past the baffles
and enter the leach field. This is not good. It clogs things up.

If the sludge layer on the bottom gets too high, then sludge will exit
the septic tank and get into the leach field. This is not good either.

Additives are useless. Some additives are even worse than useless:
they have chemical properties that act to keep fine solids in
suspension (instead of sinking to the bottom where they belong). These
fine suspended solids are carried out the tank along with the liquid
into the leach field, and they eventually clog up the leach field.

We have a family of 5 with a 1500 gallon septic tank. I had the tank
pumped 5 years after purchasing the home. I watched the whole process
and spoke with the guy. He said I could have gone another 5 years no
problem. So it all depends on what you put down the drain. We have
no garbage disposal; we use detergent instead of bar soap in the
shower; we don't flush the "wet wipes", etc. We do use bleach in the
laundry. The showers, the toilets, the sump pump, and all the sinks in
the house go to the septic (we don't have a separate dry well for gray
water).