This subject may have come up before, but have not seen it.

What would you think about running a small airpump that pumped air
into the discharge port of the holding tank (so that the air entered
at the bottom of the tank) to aerate the fluid in the tank?

I know you favor lots of air circulation in the vent circuits, But my
tank installation leaves almost no room over the tank and the vent
line routing is quite convoluted and of small diameter (no way to fix
this short of destroying the usefulness of the aft cabin)

Gwynne Spencer