We drive between camp sites with 1 gallon of bleach in each tank and all fixed. Only need once and we tested 30 days later no issues.
Also we use tst gray tank & a black tank cleaner after each dump
Key is bleach permanently eliminated our smell after 1 trip
I tried the bleach in the tank, only to cause other problems. At least in our experience, the rubber-like seals in the gate valves swelled up enough to make the valve not shut all the way. To the point of needing to replace them.
Now I will admit, I was also intermittently trying other products, like Lysol. But I never combined them at the same time. But it was the bleach that I used more often.
Seals in the toilet ball where you flush, seals at both gate valves, as ours crosses over to the driver's side.
Since we don't add those harsh chemicals, those seal failures are bygone. The odor is the only recurring thing, and only after a week to 10 days before dumping the tank. We now use the electric exhaust fan above the toilet, that seems to help well, until getting to a dump station, then there is no worries.
Just saying be careful using those chemicals in those tanks. If the gate valve starts to feel a little harder to open, then not wanting to close all the way, your seals are swelling and the gate valve is starting to fail.
**edit in: FWIW, I, at least, will use the campgrounds facilities more often than in the RV, to help in the "cause"... lol
