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 ...
hate to tell you this but bleach and urine do not mix very well. I bought a product called Happy Camper and I use it in both tanks. this stuff works great. even during the hot months of the year. go on line to buy it.