"Capt. JG" wrote

I just attended a diesel seminar on Saturday put on by one of the local
yards. That black crud looks very similar to the bacteria that they showed
us. Is that what you have? You might want to look at it under a
microscope. If so, they recommend a biocide (any will do, mentioned was
Biobor)

I use Star Tron which is an enzyme that causes any bacteria present to
detach from the tank walls and clump up so that it can be passed steadily to
the filters instead of going through all at once when stirred up in rough
water which is usually when you don't want to deal with a clogged filter.
It's a non-toxic alternative to biocide. I put it in with every batch of
fuel since each refueling can expose you to new bugs. I'm pretty sure it
works because I had a lot of stuff show up in the sediment bowl (pre
polishing system) right after I started using it.


According to the yard manager, who has about 30 years experience, one
should top off the tank as much and as often as possible as any
condensation is ultimately bad. He keeps a jerrycan with fuel in his
lockbox, so that when he returns and has only used a small amount, he can
top it off.

I see you missed the long thread on topping up tanks. Just because he did
it for 30 years doesn't mean it's necessary. Read the thread and come back.
Minimizing the surface area of fuel in contact with the air is a good thing
to do but it's a crazy obsession in the actual hassle/benifit analysis.


FYI, all #2 is identical, at least per state. You want to ensure that your
diesel has the right cetane number, typically in the 48-51 range, and if
yours is like ours in California (41 - mandated by state law), then you
can get a stanadyne additive to bring it up. Apparently, many of the long
haul truckers fill up in Nevada before they cross the border, since Nevada
serves the good stuff.

Now, this is interesting. I want to find out more although I expect Maine
isn't mandating weak fuel.


He also recommeded a dual primary system if you sail offshore.


That's essentially what I have although one of the filters is of higher
retention capacity and running separately all the time.

Another aspect of my system is that the fuel is being sucked from the tank
much, much, faster than the engine would draw (and this is especially an
issue on my Yanmar where the return line doesn't go to the tank). This
means that crud drifting around just below or near the pickup is
significantly more likely to be drawn in and recirculated through my big
Shelco filter.

--
Roger Long