About Dakota wrote:
water gets too hot in the summer, and it's too cold in the winter. I
had two ponds, but now I have none. In summer, depending on the day,
the water could reach a temperature of 110, easily, with direct
sunlight. Two days later, the water might be 55 or 60. In the winter,

Let me guess, a shalow pond with a black bottom? About the worse thing
you can get for fish... Our pond never gets over 78-80 degrees, even
in the middle of August when the air temperature never drops below 75 and
is usually over 100. It does get shade in the middle of the day and it's
3 feet deep.

however, it is not unusual for a temperature to be below -30 for weeks
on end. After a while, I just became to frustrated to keep on doing it.

I'm pretty sure there are folks up north who have ponds. If you are interested,
you could ask on rec.ponds how they do it.

--
Victor M. Martinez

http://www.che.utexas.edu/~martiv