I designed this tank with multiple tappings and two baffles. There is a supply/return for the engine, supply/return for a diesel fired cabin heater and a supply/return for a dedicated fuel polishing system. I did not install tank clean out ports because access to the top of the tank is extremely limited. I will eventually remove it and install clean out ports but that is likely 10-15 years out, if at all, with this polishing system. I have a friend with a very high quality scope camera that we can inspect the tank cleanliness with in the mean time to assess any need for physical cleaning.
When designing for a fuel polishing system I definitely wanted to get my polishing pick up directly over the deepest part of the tank in order scrub/polish every last little bit of the fuel. This pick up tube is 1/8" off the dead bottom of the tank and directly over the V where any crud/bugs/algae or other junk would naturally wind up.
In order to avoid foaming with a high flow polishing system the return for the polishing system is also returned via a dip tube. Returning the fuel below the level of the fuel prevents and or greatly minimizes the potential for fuel foaming. If you click the photo and make it larger you can see a drawing of the pickup or dip tubes and the supply/return tapping locations.
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