The issue of what goes on in your black tank, well, is something of a black hole. I do my best to obfuscate the issue with the following:
I'm on week two of my scientifical , observational test of "Tank Tech RX" as others here have suggested. My observations are just that, and in no way am I one to criticize others or their opinions. Now, for the news:
I use a clear elbow as the first thing connected to my waste tank, so I can see what is going on. Too many times I have closed the black valve on some debris and then have to deal with the clog in the valve. So I let the black tank flush water rinse the tank until I see nothing but clear water coming through the elbow, then I shut the valve.
Using Tank tech RX I have see no difference in the poop count, tissue tussle or other black tank criteria. I doubt it has done anything but to relieve my bank account of $42.95 at the RV store. One clue may be its 'ingredients'; Structured water (??), lactic acid bacteria, molasses and rice bran. AFAIK, cellulase enzyme is the only thing that can break down toilet paper (cellulose). As far as odors, no change noted, but I never have smelled a black tank odor anyway. Tank Tech instructions say "90% of odor problems are caused by insufficient water in the tank."
So I'll continue with my scientifcal observations of Tank Tech RX until the quart bottle is empty. I'll let you know if something different happens with my black tank.