Dan Valleskey valleskey at comcast dot net wrote:

What about the stuff they add to an RV's holding tank? Not sure what
it is, deep blue in color, if that helps. Coleman sells it, or most
RV stores have something like it.=20=20=20

That sounds like Blue Goo. It works but promoted sloshing-around.
Whereas Odorlos (Od=F8rl=F8s) is a dry powder.

Google brings up lots of hits for it, so I'll investigate.