Concerns were expressed on this thread about pulling too much flow thru a
polishing filter. I polish with a Racor 500 in a stand-alone system. Some
time ago I called Racor and found out it's cartridge is rated for 20-25psi.
I equipped my polishing system with a vacuum gauge, same as on my engine.
Vacuum can then be monitored and regulated in a couple ways. One way is
variable speed pump. The other uses a bypass valve, so that not all fuel
being pumped goes thru pump. I'll usually keep the filter vacuum around 10
psi to be conservative. When it rises 5psi that's sign the filter is getting
clogged.

As for stirring up the crud, one guy told me he shoots a jet of air around
the bottom of his tanks. Has a small L-shaped copper tube on an air hose,
and with it tied to a dowel/rod pushes it to bottom and "aims" it around.
He'll them sometimes just let the thing bubble away while polishing to help
keep particulate matter in suspension.

Before "bubbling" the tank or doing anything else, first pump a quart or two
off the bottom into glass jar and check for water. And continue this,
discarding the water, until no more is seen.

FWIW.
Len

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