Don't have true polishing system but do have filters in run from tanks and on return to tanks as well as the usual twin Racors and the filter on the engine.
They have portable polishing systems both down in the islands and up in the north east. Is it advisable to get this done and if so at what intervals.
An article by RichH;
As one deeply involved in filtration engineering for almost 35 years .... recirculation polishing without FIRST cleaning out the tank IS snake oil ... and will only 'temporarily' --- say again TEMPORARILY clean the oil.
Recirculation polishing prevents the 'growth' of particles into larger and large size, and removes the 'seed particles' (mostly bio-forms) from the fluid. The constant removal exponentially decreases (and removes) the amount of particles.
If you dont periodically inspect and clean the tank walls, those particles 'stuck and growing' (growing fungal filaments, etc. and agglomerating sticky gel-like particles) only become the seed particles for new and larger particle 'growth' ... AND when the matt-like 'colony' of living particles break loose (because of dead and dying micro-organisms) they rapidly 'slug' the previously cleaned up oil with an exponential amount of even more particles.
Recirculation polishing removes the particles before they can affix to the walls; but, it cant remove those particles from the walls if they have formed a 'sticky colony' (calcyx).
Recirculation polishing of a fouled tank is of NO long term benefit. You HAVE to start with a CLEAN(ED) tank.
Follow this link: Cleaning a fuel tank
and/or do search on the sailnet site for: cladosporium
The purpose of a recirculation polishing unit is keep the fuel in a pristine/uncontaminated condition by continually removing the 'seed' particles that are the source of such 'growth' - biological particles, & small 'gel-like' particles that continually agglomerate into larger and larger particles, particles that are 'excreta' of metabolism of such fungals and bacteria - asphalt-like resinous compounds. The common microorganisms found in diesel oil or all 'resin formers'.
Most filters used for 'polishing' only have about 35 to 50 grams of dirt capacity; thus, easily 'choked' if the system is already grossly contaminated; the recirculation system is used to prevent fouling - hence my caution of 'snake oil'.
A recirc. polishing should only be used in a throughly cleaned tank (+ with biostat/ disinfectant added, to help depress growth in those areas of tank that do not actively become 'pumped', such as the 'corners').
That stated, a recirc polishing system 'can' be an adjunct to tank cleaning; but if and only if - the tank is heavily dosed with suitable enzymes (chemical 'tank cleaners') that emulsify the 'goo' already adhering to the walls and which puts the particles into solution or dissolves them .... hopefully to a µM size smaller than the retention rating of the filters. The downside is that such emulsions of asphaltics dont 'burn' well; hence, you risk having such 'fuel' not completely burned in the combustion chamber and simply settle out and form thick deposits of 'coke' in the hot surfaces of the exhaust portion of the engine and downstream. Best is to bite the bullet and get inside and scrub out the tank before engaging any recirculation polisher.
Recirculation polishing systems are only to 'maintain' tank cleanliness - to prevent/retard 'growth' inside a tank.
As I read this, don't waste your time installing your own or having someone else do fuel polishing, unless you are starting with new, perfectly clean tanks. Your filtering system should be perfectly adequate for it's job.
Now you can buy me a G&T w/a lime next time we are in the same bay somewhere, with all the money I've just saved you.