Can't speak to Rid X. If you are having real odor problems because of heat build up reverse the flow on your vent fan to pull air in and turn on. When you flush any odors will go out the stack. If you have a vent fan on anywhere, in the coach when you flush it will pull odor from the tank, into the coach. These things are pretty tight and any vaccum is going to pull from any source.
We use the Camco stuff for both black and the gray water stuff for the gray. t smells like lemon. If we don't empty the black tank in say a week we add more stuff but it's inst neccessary. If we have to empty the gray tank, we will flush the black tank too, much of the time.