I always add one of the sachets/pods, after I have dumped the black tank. Whatever that stuff Walmart sells is called. Doesn't matter how long I think it will be before going out again. And for this last season I have started dropping a dishwasher pod at the same time. Just for a little low-suds dissolving of greases. I've never had any problem odors to deal with.
I don't think anyone can prove the tank treatments do, or do not, do anything that I couldn't live without. But if I was too cheap to spend a few cents on a little additive, I would just sell the camper and sit in my recliner at home.
