I had months of algae/fungus problems with my 300D. I used boicide and it didn't go away until I used StarTron Diesel additive...It works via enzymes and since I used it I haven't had to change filters once. Also available at Boat supply stores...like West Marine

http://www.starbrite.com/prodcatalog.cfm?ProductCat=Automotive&ProductSCat=Gas%20%26%20Diesel%20Additives%20%28Auto%29

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."