Many thanks for the reference, Tony; I don't know how I could have overlloked the article in Winter 2006. The line diagram is very clear and corresponds with the system I had sketched out. Herman: thank you for the offer. I presume the daytank is a Vetus 25 litre plastic tank (Robert Chave's was). I am guessing that the fuel overflow back to the main tank has been fitted by drilling the wall of the day tank a few centimetres below the top. Is that so and what diameter of hose/tubing is used? I had thought that the best arrangement for the daytank vent would be to tee it into the main tank vent in a way which provided for an emergency escape route for fuel back to the main tank in the event of the overflow becoming blocked/air-locked. Does the day tank on Brian's system have a separate vent? I am proposing to site a day tank immediately above the main tank so the common vent would be easy to arrange - it may not be so convenient on your installation. After much thought about the material for the main fuel tank (inevitable corrosion, inside and out, of mild steel versus weld corrosion in stainless) I have opted to install a 220 litre Vetus plastic tank in place of the starboard pilot berth on my Catfisher. The decision was helped by reading Nigel Calder's (Boatowners' Mechanical and Electrical Manual) opinion that plastic was ' .. the material of choice'. This tank has no connections through the tank wall (all via the top cover plate) and I'm a bit reluctant to cut one to feed the circulating pump. Is the Facet fuel pump low enough to remain flooded with fuel when it is stopped, or does the system rely on the pump developing a self-priming suction on start-up? I have tried to get information on these pumps' ability to self prime when dry but with no response from the manufacturers. As these are automotive fuel pumps I should perhaps go to a petrolheads chat room! If I mount the pump below the base of the tank, feed it via the top cover and discharge to the vented space of the day tank, the fuel shouldn't syphon out and the pump should remain flooded when stopped - once primed in the first instance. The level in the discharge pipe leg should settle at the level in the main tank. But I would really like to know if the pumps have a self-priming capacity when dry; for those embarrassing moments when what shouldn't happen - does happen. Thanks if you can help Geoff Butt