drop in a 300W heater
(http://www.aquaticeco.com/index.cfm/...etail/iid/9082)

you will need a bucket filter
http://weloveteaching.com/puregold/c...re.html#BUCKET

and an air pump with a couple of air stones. make sure this both high
enough that water will never get into the hose AND that it is covered
up to keep water and snow out.

Then drape the whole thing with plastic, like a hoop house or an A
frame so that there is a couple feet above the water at the highest
point. this will keep in the heat.

Most of use up in the frozen tundra keep out fish out all year but we
do take measures to protect them, keep a hole open, AND something to
extend the season a bit longer in fall, bring the temp up sooner in
spring. my water gets below 50oF only 1 month of the year, the rest
of the time I feed them a couple times a week. Ingrid

On Fri, 27 Jul 2007 20:03:03 CST, "AL Z" wrote:
I have a 6 foot by 2 foot by 2 foot pond that was formerly a cattle trough.
It has a liner, fountain, and is buried approximately 20 inches in the
ground. I need advice on the best way to help my goldfish and koi survive
the harsh Chicago winters.