On Thu, 20 Nov 2008 16:02:33 EST, Peter Pan wrote:

I thought of shutting off the filter, but then what about the Bio
Load? Without water running through the filter, you'll loose the
helpful bacteria

You will lose your bacteria if you shut off the filter. Under 40F bacteria
creates a bio-film to survive cold temps, but still needs O2. Come spring,
much quicker start up time and less WQ problems. (YMMV depending on fish
load and filter size.)

Freeze-wise, as long as water is flowing, no problem. The problem is when
power goes out during below freezing weather, if the pipes don't self
drain.

Most ponds under 4-5 feet rarely stratify, and, ime, it is better in small
ponds to continue circulating slowly so fish aren't laying in their own
pollution. I know I've had healthier fish since I've left the bottom drain
connected. ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us