It is rare that I would argue with you John, however....

I did not find anyplace in those that explained the phenomena of "asphalt" being a by product of treating with biocide. I am pretty sure there is a scientific definition of asphalt that does not include being produced in a fuel tank as a by product of using biocide.

They all appear to be advertising web sites.

One of the websites stated that the way fuel is refined is much different now than it once was. I don't have any knowledge of that. Has it changed in the last five years?

I know the sulfur has been mostly removed, does that impact the bacteria growth?

Every time I have found my filters clogged with black specs I have changed filters and treated with biocide and had no further problems.

I have driven a lot of miles in diesels, having owned ....25 or so and have never cleaned or replaced a tank strainer (that I can remember) or removed a tank for cleaning.

I do know that every site you linked offered a product which would solve all problems with bacteria....nothing wrong with that but I think we all know that advertising often parades as science but seldom is.

Have a happy valentine day!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.