Our 2003 Minnie came with an AquaMagic 4 toilet. We found that we couldn't drive with the cab windows or roof vents open because we would get black tank odors. The source of the odor always seemed to be the toilet, but no amount of sealing around the floor connection resolved it. The only thing that helped was installing a
360 Siphon on the roof vent.
Two years ago we drove across southern Colorado to Mesa Verde. When we opened the bathroom door at the campground the stench from the black tank was unbelievable. To save our trip, I did some creative sealing with masking tape over all of the toilet front and back openings. I sealed ziplock bags with tape over the foot pedals so they could move and still be sealed off from the opening. Thankfully this solved the problem temporarily.
When we got home, I did a lot of online research to find a replacement toilet. All of the available toilets had some negative reviews, but I finally settled on the
AquaMagic Style II. This toilet had a drop pipe into the black tank and the only seal is on the shaft for the waste ball. We have had no issues with the waste ball holding water in the bowl and no issues with odors any more.
We can now ride with the windows open!