Hi Bob, I wouldn't be quick to dispense with anything which insures a supply of clean fuel. It's well above most everything else on my priority list for equipment. Until you have struggled to change a hot secondary filter and then bleed the system with the boat in extremis and rolling in a seaway, you won't appreciate it. It could save your life. Here's a description of how Seahorse is set up. She came to us this way and we have not changed it. It is my understanding that this is how it's done on the PNW fish boats and I have the utmost respect for how they do things there: A Racor 800D-OF3 fuel "blender" which incorporates two of the 1000 series 10-micron filters (in parallel) with an Orberdorfer pump. It transfers fuel at about 3 GPM. This system is entirely separate from that which serves the main engine, and has its own 1/2" suction and return lines. The suctions go to the very lowest point in the tanks, whereas the main engine suctions are about 4" off the bottoms. Believe me, when this unit operates, those Racor "turbines" spin that fuel! Before we take fuel, we transfer what remains in the port tank to the stbd tank through the "blender," then fill the port tank. We always take the suction for the main on the stbd tank (which has already been filtered) and as that fuel is used, we make up from the port through the "blender." The main has its own supply through either of the two Racor 900-series 30-micron filters, thence to a 5 micron Lugger (Deere) filter on the engine. We have found that it pays to change the secondary filter after it has passed about 500 gallons; the primaries can handle twice that amount. I suppose you could say that this is a tertiary system, however, I would be happier if the main engine secondary were available in 2-micron. BTW, no offense, but I dislike the term "polishing" when applied to filtration. Another marketing buzz-word. Having come up through the hawsepipe I have done plenty of polishing and it had nothing to do with fuel. Regards, John "Seahorse" > The largest part of the argument against a polishing system is a perceived minimal return on investment. The polishing system is expensive and there is (almost always) a way around needing it. Instead of arguing the pros and cons of polishing, why don't we brainstorm a creative way for our PMM to get both polishing and final filtering done without duplicating systems? **************Make your life easier with all your friends, email, and favorite sites in one place. Try it now. (http://www.aol.com/?optin=new-dp&icid=aolcom40vanity&ncid=emlcntaolcom00000010)