[ReelMagic]

Not sure if you are aware but the vacu-flush system is located in the engine room under the floor where the ladder is. It's against the forward bulkhead. I agree, cleaning the tank itself, located under the aft floor grate in the engine room. You may want to flush the entire system with fresh water, pump it all out and see if that helps.... Another cause may be the toilet itself. Does the toilet hold water or is it leaking down? If leaking down then I suggest you change the ball seals in the toilet itself. Gases could be coming back through the seal. Does the system hold vacuum M2C