It works on the odorant (I said to use it, pH adjusted etc) but *not* if
the odorant is trapped in grease/goo/crud. You need something else to
mechanically bust that up and out.

Looks like Richard has a point on this job. I soaked the tank in a strong
shot of bleach full of water overnight. Its no better this A.M. Looks like
my plans to use this tank in the house are off till spring. I'll leave it
outside all winter. Maybe time is the cure.

Karl