Seems to have lots of good reviews on Amazon. Please let us know what you think.
I've found one way to combat odor is to make sure there is water in the bowl after flushing, enough to cover the seal. Another is to use plenty of water if connected to sewer. This is difficult if you are boon docking or don't have sewer.
I'm also using the Geo Method. No odors at all. We are seasonal and empty our black tank after about every 3rd weekend. I also spend one to two weeknights at camp and go to work from there in the morning. I use two capfuls of inexpensive laundry soap after emptying my black tank. I also add the laundry soap to the gray tank in the bathroom. I feel like the galley tank gets enough dish soap with use. I've never had an issue with odors from my gray tanks. I suppose even using a capful of the good stuff we use for laundry wouldn't be a big deal every 3 weeks. Then I do the water softener at opening, mid summer and around labor day. I get the water softener on Amazon. Hard to find at Walmart and the brand name is expensive.
Have to say my tank sensors are more accurate since I started using the Geo Method as well, but I don't trust them anyway. Good luck, hope the Happy Camper product serves you well.
https://sites.google.com/site/cbruni/