In the South Florida climate, stuff grows on anything that is not moving (and somethings grows on anything not moving fast enough). I have had diesels since 1989 and never had any diesel/alge/growth issues untill.....

Last month I filled up both my 1980's era 300SD's at the local fuel station, within a week both cars started sputtering and dieing on me. The prefilters started looking as black as night. I pulled the fuel tank strainer off one tank and thought the Creature from the Black lagoon was living in the tank from all the crud. Ending up pulling the tank and stream cleaning it along with a new tank strainer.

Same with the 2nd MB (although not as bad)-I now use the star Tron from the local marine place.

I guess you can only temp the devil so many times before he gets his due.