When your knee deep in the beasties find a log to stand on. And be thankful their not waist high.
Here's a couple of links about people that have had this problem:
With Pictures Cool:
Filters, Fungus, Biocide, etc.
Pick up a bunch of filters.....
It should be a nice ride once you get the beasties....But remember any vehicle over 15 years old is a project.....