Freaky UV thingy happening

["Bodin Family" <bodin1 at gte_net>]

Gang,

Over the last month-to-six-weeks or so, my UV stopped working on my 4Kgal
pond (http://home1.gte.net/bodin1/The%20Green%20Fin.html#_The_Big_Pond). The
bulb is ~six months old, so I figured that there must have been something
else wrong. When I pulled it apart week-end before last, the Quartz tube was
COVERED with 1/16-1/8" of mineral scale!

Well, I cleaned it with some HCL (don't try this at home, kids) pool acid
and after several rinsings, the quartz tube was good as new.

Thinking this was the solution to the problem, a week went by without any
decrease in GW in the pond. It's GOTTA be the bulb (or so I thought)... so I
ordered another bulb (it should be in here in a few days). But for kicks,
tonight I pulled the unit apart to look at the Quartz Tube again and... It
was covered with a frosty new film of mineral.

Any molecular scientists or quantum space-time physicists out there able to
give me a clue as to why this is happening and what to do about it?

p.s. Any good Koi/Garden pond mail-lists out there? There used to be
PONDS-L, but it is now gone (and it was focused mainly on agriculture
ponds).