ON 20050105@4:45:18 PM at page:
http://www.massmind.org/techref/other/pond/index.htm#38357.698125
James Newton[JMN-EFP-786] Says

The plants don't seem to have done all that well... the heat followed by cold snaps this winter have all but done them in. The mosquitoe eaters have done well, but spend most of thier time quiet and deep when the temperature drops. The bottom of the pond is at 42' and steady while to top varies from 44 to 65 with the air temperature from 50 to 80. 
<P>
Some form of insulation (perhaps a good plant layer? or floating bubblewrap?) is going to be required along with heating if there is any hope of growing talapia. 
<P>
A local "going out of business" sale at a place that does water filters yealded two pumps for $25 each and I "dummied" up a bamboo flue from the roof of the porch out over the pond. The resulting drop is about 6 feet and provides more than enough aeration with only a very little "splatter" so I don't think water loss will be a problem. The pump draws 75 watts so that is no more than a standard lightbulb. I'd rather use wind power, but the pump will be an acceptable alternative and a good backup when the air is still at night.