Nothing is needed to be added to septic tank. The biological activity occurs inside of the tank naturally. Pump the tank every 5 years is normally enough. Baking soda won't hurt or help, and no homemade solutions are needed. Every time tank is pumped, they usually check the inlet and outlet T's, look for cracks around the pipes, and make sure lids are in good shape on conventional systems. On alternative systems, they need annual inspections and do maintenance on any pumps, baffles, etc as needed. I've seen many tanks that were installed back in the 50s and 60s, and they still work as good as new today. Occasionally a distribution box needs to be adjusted or replaced. There are many types of septic systems, best for owners to learn what type they have, and maintain as needed. https://www3.epa.gov/npdes/pubs/homeowner_guide_long.pdf

Have had one all my life.  Never used anything, but it also depends on a few things.... like don't overuse bleach, don't have a garbage disposal, don't use charmin.  If you do any of those things don't pump any less than every 5 years or you could have major problems.  Also don't plant anything more than grass over the drain field.

IMHO, a septic system is no place to "try" homemade solutions.  35 years in my house, never needed any additives.

You have some well-informed answers here from people who have first-hand experience.  Jeff Pearl provided a resource link. 

Fred,

Clueless, never had septic...but you have good answers. A

Who the heck knows. I've only sold 2 homes with them.

I've had a septic system for 22+ years. Septic additives are unnecessary and what we've always been told by septic specialists. Biological additives don't help or harm the system. The system gets all the bacteria it needs from the incoming waste. Chemical additives - degreasers and drain cleaners can harm the system, upsetting the pH balance, killing the bacteria the tank needs to run properly.

If the system is overworked, use less water or have the tank pumped more often. The time between having it pumped will vary from family to family based on usage; size of the tank and number of people living in the home. It's best to monitor the system and become familiar with how often it should be pumped based on usage. Ours for example use to be every two years, now with less people in the home it's every 3.5 to 4 years.

I know nothing about septic tanks, except that they need to be inspected before I let a buyer purchase a home with a septic system.

I have a inspection that tells people with them about Rid-x all the time.

You have some good answers. 

Parents built a house in the 50’s and it is still there. Never added anything and it is still working fine. Probably been pumped,three times

I've never lived in a house with a septic tank. I've sold many homes with septic tanks. I've heard my septic inspectors say do use those things as it shouldn't be needed. The company I use provides thorough information for homeowners who purchase homes with septic tanks. I don't advise my clients in these matters other than use a professional and knowledgeable inspector.

We never use anything in the septic, but in our area pumping is recommended every two years, at most three, depending on number of people living in the home. 

YES, ROOT KILLER is important IF your tank is anywhere near trees with roots that can 'travel' . . . otherwise I agree with Jeff P that the magic in a septic IS natural . . .

new used it, never had a problem.

Fascinating as it implies benefit but as to results? Your question stands

To keep it healthy use the right toilet paper and very little of it. Start a compost bin for vegetables cuttings rather than disposal. Don't put bleach and drano down there.  I do not think you need to add a product or yeast. Baking soda is base or alkaline so that really depends on how acidic your water source and stuff you put down the disposal are. Cottage cheese -no idea why that would help. Yeast is one of the ingredients in Rid-x.  Jeff Pearl  has the answer

It doesnt matter, just dont put anything down there that will hamper decomposition like bleach.

Septics are quite common in our area and depending on the number of people in the household, the main reason for failure is adding unneeded chemicals or homemade solutions OR pumping too often!!   It used to be said that pumping should be every 2 years but now it is more common to be pumped every 10 years.  There is nothing worse than an empty tank at the beginning  of the cold winter deep ground frost!

Septic systems are quite common in my market and my trusted septic pros discourage additives like Rid-X.  

Here in the urban area where I live and work, septic tanks are rare. I can't offer any advice.

I know there others here who are well versed in that area.