When I first got my boat, I shocked the fuel system with Soltron, then
had it polished. Have used Soltron for the last 5 years with great
success. Developed a tiny leak from a tank seam awhile back. Opened the
tank and coated the inside... there was almost no slime in there, just
some stuff on the bottom of the tank that looked like rust that had
fallen from the top where the diesel almost never sloshes. The only
other thing I add is 1 Qt. of Marvel Mystery oil per 100 gallons of
diesel at fillup. This is per Bob Smith's recommendation over at
American Diesel. He says this makes up for the lower lubricity of the
new lower sulfur diesel fuels. Will help keep your injector pump from
wearing out prematurely.

You can read about Soltron at: http://www.navstore.com/Soltron.asp but
you can buy it at West Marine, etc. now... Starbrite has the retail
distribution rights. It's an enzymatic treatment, NOT just a biocide.

No commercial connections, just a happy customer.