Usually use Thetford with the dissolvable packets. As I said I tear open the packets and throw away the bag as I don't want them to stick to the contacts for the sensors. I also will dissolve them in warm water before putting it down the drain. Just be sure to buy the waste dissolving enzymes, not the deodorant. The deodorant does very little. I use the same stuff in my septic at home. It is the same stuff I use in the blackwater tank.
2017 Crusader 315
1995 Ebbtide 150 Horse Johnson (etc)
Former Montana owner
Colorado Cruiser, Over the Pass and Down the Hill