We finally settled on Happy Camper too. Easy to use and not expensive ... great stuff!
We HAVE NOT spent hundreds of dollars on black tank additives over our RV'ing years ... it's not that expensive adding something to help break down what's in your black tank and thus keep odors down. When I dump the RV's black tank I like to see (through the clear plastic elbow in the line) liquid coming out - not chunks of stuff. ;)
Full-timers who keep their sewer line hooked up most of the time of course can get by with only water in their black tank here and there during short drycamping periods when they're not on hookups. When we go on RV trips, it's mostly drycamping and we don't have to dump our black tank very often (thank goodness) because of it's capacity for just the two of us. It's then that one needs something in there to help with odors and breaking down of the sludge. We have lived with a septic tank in our stick house for 37 years, and every month have added a bacteria substance to keep it clean. We have only pumped it once in 37 years as a permit requirement for a remodel project, and even then the technician said the tank was in good shape when he opened it.
We don't want to carry around an RV tank full of fermenting smelly stuff for 2/3/4 weeks between dumps when on our RV adventures - especially in warm weather when we do most of our traveling and camping.
