I have to share this solution with everyone! I’ve lived in an RV for five years now, and if you have lived in an RV for even one weekend, you likely know what the main challenge is (or one of the main challenges) . . . that blank tank. How to keep it from smelling.
There are lots of treatments out there, I’ve tried many of them over the past several years. I can’t use the ones that employ perfume as their main remedy because I’m sensitive to it, so I use the ones that are scentless. Some work better than others, but over the past few months, I’ve tried an idea that I came up with all by myself. And it works! And it’s cheap! So I have to spread the word!!
Take a bar of cheap soap; cut it in half, and send it down to the black tank. This is how I do it: I drain the tanks, then close them up, then I run what I imagine to be about two inches of water in my black tank. Then I put the bar of soap down there (remember to cut it in half–if you try to send it down whole, it will get stuck). I leave it to sit all night to give it time to dissolve a bit. I’m not a scientist, but I think bar soap can do a number on bacteria fairly well, and it also has a slippery quality to it. Between those two things, this idea seems to work really well. I hope it will help you, too. Let me know if it does!