A septic system properly installed and maintained should never have to have an additive. It's been a few years since i worked on a septic system, but i found the biggest problem with them was grease from the kitchen and cigarette butts. Pumping that frequent for one person seems excessive. Another killer for septic systems is the paper you use. Make sure the label says suitable for septic systems.

A properly operating septic system will have some solids on the bottom of the tank, mostly liquid, and a scum layer on top. The scum layer does not exit the tank UNLESS you use additives. Additives serve only to break the scum layer up into smaller bits which then exit the tank and cause problems in the drain field. Never, never, never, never, never use additives in a septic system. Your sewer guy is absolutely correct. If he wanted to pump the tank more often and replace the drain field (big money) he would suggest you use additives monthly and offer to sell them to you. Research first, then offer advise.

Everything a septic system requires is in the 'black water' from the toilet.

Yeast are NOT the active microbe.

Grease can cause problems, excessive detergents and bleach, or excessive paper products.

Cellulose is NOT digested in a septic system, it collects in the tank and must be removed by periodic pumping (along with other non-digestible remains, AKA 'sludge').

8-10 years is not all that frequently for a septic system being used at its design capacity.

The purpose of the pumping is NOT to remove the liquid in the tank, but the non-digestible solid material that accumulates.

Septic tank additives are wonderful! But only for those who make and sell them.

Well, I'll probably get beat up over this then, but.....

On three occasions over the years, I've encountered flushing that became gradually slower and slower while all my other lines remained free-flowing. I poured some rid-x in them and flushed. By the second day they were free-flowing again and have stayed that way.

asolo - Enzymes can be helpful clearing a slow drain, and while the three occasions may have caused a disturbance in your tank, it's not the same as continued use such as that recommended by the folks that sell the additives.

"I've encountered flushing that became gradually slower and slower while all my other lines remained free-flowing". That would be more indicative of a toilet or pipe blockage problem than a septic problem.

Don't all the toilets in your house run into the drain and then that main runs to the septic tank?

@justalurker...

Agree toilet or pipe obstruction, not septic tank problem. Concerned I may have taken the thread off-topic with my anecdote.

Don't know plumbing layout but I have seen from the septic-tank side during pump-outs that there is a single inlet to the tank so, yes, there must be a "main" that they all feed into.

@aliceinwonderland...

Agree "continued use....as recommended..." is silly. The stuff isn't cheap either. Agree septic systems should and do work quite happily without it. Never talked to a plumber or pumper who recommended regular use of it like the mfgr's do. However, I have talked to several who did recommend it upon my description of my symptoms....which is where I got the idea. Each of these occasions were one-time events.