I sold a house last year and the owner did not even know were the tank was and never had a problem. His Dad purchased the home in 1969. I am one that on the old fashion systems if there is not a problem do not pump them. Once you pump them is when you ahve to get the bacteria working again. and like one said if you are putting a lot of bleach or something else that kills the good bacteria you need to be adding something to help it get started. Have never heard of dog food. You can use Yeast but from what I have heard that is basically what Rid ex and some of the others are
I grew up with septic and we had disposals
good luck
Don
Don, I don't think any septic system design allows for the modern automatic washers and dishwashers that are the standards in our homes. My neighbor has the identical aerobic system as I do. He puts his laundry water through it, and every four months, his filter is clogged with 1/2" thick gray sludge from the laundry lint. On the other hand, my filter has a thin brown coating that rinses away with a hose. (My installer carries a sump pump and drops it down into the the final fresh water tank to pump the water he needs to clean off the filter. Slick!) Of course, I'm talking about an aerobic system because they are the most modern type of septic system. I think anyone who sees what a washer can do to that type of system would take positive steps to keep the laundry water out of the septic. How much sludge inside conventional septic tanks is due to laundry waste (lint and other solids)? I can't say, but I'd sure like to see two exact conventional systems side-by-side with one of them having a grey water drain.
In my case, my builder put the washer drain into the sewer, but I redid the drain to make it a grey water drain. I run the water out on top of the ground to evaporate and my grass loves it. The phosphates make sure the roots are good and the grubworms are few.

When it rains, the runoff spreads the laundry "contaminants" out over a larger area than if they were confined inside an absorption field. Sunlight is a mighty decomposer to boot.
Don, I'm sure you can have a septic system that functiions without special maintenance if you are careful with bleach and detergents. I just don't understand why we have to put anything into septic tanks that will endanger or kill what makes them work in the first place.

If city codes say you have to do it that way, so be it, but I will continue to divert my grey water until the county demands I do it another way.