In the past we stayed for several months in the same RV park in our MH. We used Exodor Bio-Pak drop ins for the black and gray tanks. Sometimes there was a horrible eggy smell when we dumped the gray ...
We had a bad smell from the bathroom area last summer. I did everything and added everything I could think of and nothing helped. I finally took the cover off the compartment in the basement under the bathroom. There was a puddle urine there. The smell was actually coming from the basement compartment rather than the tank itself.I took it to my RV repairman and he took care of the problem.