Related:
Maintaining Your Septic Tank
According to this link-- http://www.ext.nodak.edu/extnews/newsrelease/2006/030906/11avoidu.htm -- additives aren't really as effective as we think they are. Either way... I don't see any harm in it. I've been using bakers yeast for my system.
And you should be able to get it at places like Whole Foods or baking supply stores.
Cheers
http://uncouthpalate.blogspot.com
If you don't want to use yeast, you should look at BioWorld Produst septic tank treatment. It has worked GREAT.
http://www.adbio.com/septic/septic_treatment_unit.htm
Roughly speaking, how much brewers yeast should you use per month, per year, etc.?
Editor's Note: Here is a great link for Septic Tank care:
http://www.co.el-dorado.ca.us/emd/envhealth/homeowner_septic.html
It looks as though yeast is very helpful in tanks that are sitting, such as vacation home tanks but may not be as helpful for tanks that are being used all the time.
That stuff doesn't really help but it does not hurt the system. good information about septic tanks and treatmentat http://www.septicdrain.com
good luck