I posted this in the past. A proper additive and circulation thru a
Racor like filter will slowly clean your tank. The additive will dissolve the crud over time and the filter will catch it. If you have engines that
pump and return large amounts of
fuel, you don't need the circulation
pump. With a vacuum gauge at or after the filter, you can see if the filter is becoming clogged.
My
current boat has 1942
steel tanks. There were no access
ports and the
boat sat for 6 years before I bought it. With 3x the additive and 6 year old
fuel, I idled the mains until I felt confident the boat would be reliable to the fuel
dock. Then I added 3x additive to the new fuel and did a 40 mile sea test. Each fueling I use a 1x additive and in 2 years, when I finally tore out the
galley to get to the
tanks, cut
ports, and entered, the tanks were clean. Only fuel, no
water, no crud.
I used Algae-x, and now I use Archoil AR6200 that I think is better.
Today's
diesel is crap. It doesn't burn as hot, absorbs
water and tends to separate when sitting for long periods. Additives in the fuel added at the refinery only last a short time. You really need to use an additive every fueling for clean tanks.