On 2008-11-16 22:48:36 -0500, Gordon said:

I think you'll find all the 70's and 80's need cleaning and the 90's
will need cleaning in the next few years. Anything newer and there is
no problem. Meaning that if your system is clean, it's probably good
for 20 years. At least, that's the way it is in the Puget Sound area. I
suppose warmer, more humid areas could be worse.

It's not that cut-and-dry. I had occasion to empty our tank to put in
fuel level sensors and such for a few seasons.

In one early-half season, we picked up enough bugs to clog our filter,
but once that lot was filtered out, we've not had a problem. A season
or two later, it was still bright and shiny.

I expect we've a few bugs at the moment, but I don't think we've used
20 gallons (from a 15 gallon tank) in 3 seasons. Lots of time to breed
the critters. Turn-over, biocide, and filtering all contribute to
cleanliness; the obverse is also true.

Amending slightly: Roger's experience from lots of turnover indicates
to me that he got some gunky stuff from the supplying fuel tanks. As
much as he burned, there really wasn't that much time to breed the
critters onboard.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/