I have one comment (at this time) to add to this thread and that's
regarding bio-media dying when temps go below 50F. My understanding from my
KHA class was that our bio-media stay active (granted less so) down to 40F.
At 40F they, like our koi, go dormant (for lack of a better term), the
bacteria supposedly make a protective film and wait for better times.

With this in mind, last year I left one of my bio-chambers in operation
thru the winter with the small pump I use to circulate during the winter to
keep open water. When spring came and I started up the other chamber using
the big pump. I saw only a tad of ammonia for 2 weeks, that I treated with
a tad of Amquell, after which the filter was up and running. I didn't even
use BZT to jump start it. ~ jan


See my ponds and filter design:
http://users.owt.com/jjspond/

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
To e-mail see website