Has or uses "Happy Camper" Holding Tank Products

I too find no need for chemicals in the holding tank.

We used Happy Camper from the time we purchased our first RV in Dec 2014, based on ratings and recommendations. No problems or odor issues. The huge tub we purchased ran out while on the road a few weeks ago.

We were moving often, could not found Happy Camper in stores. I purchased a different product, a well rated brand. From the start, we noticed odor. Not strong but enough.

I ordered a new tub online.

Just lots of water, and the Geo Method while in transit, works for us. I personally don't think there is any need for chemicals.
It's a holding tank, not a septic system. If your roof vent isn't blocked, and toilet seal is good, there shouldn't be any smell.