What is the best procedure to dump tanks while hooked up at seasonal campground site?

First topic message reminder :

This is our 1st year of camping and I know I still have a lot to learn about our 2010 29RLBS. I've emptied our tanks by pulling the black tank valve 1st, then the grey tanks.Our WC is hooked up to the sewer with a pvc pipe since we are seasonal campers. There is a hose connector on the same panel that states make sure the black tank valve is open. I have been pouring clear water down the toliet until the tank registers 2/3 full. then going back outside and emptying the tank again. then I refill the the tank to about 1/3 full (again with a bucketfull dumped and flushed in the toilet with the sanitizer packet) when we get ready to leave. We go to the site about every other weekend and have never used the toilet to go #2. But I can't seem to get some odor out. I would appreciate any suggestions.

I purchased the WC new. The factory must of had an early happy hourthe day they did the plumbing. I will be re-plumbing. Thanks for all your help