I am interested in setting up a pond outside and had a few questions about temp. Do you know the highs, lows, and maybe average, air temp, that you have the pond running in? Also do you know how much the pond temps fluctuate with the highs and lows? I have talked to some people about ponds and they all say that the color on the fish is much more vibrant after a season outside.
In Canada, the pond season (at least for me) runs from late May to about the middle of September. I've included a graph, showing the highs and lows for each month where I live. Notice the temperatures are pretty much the same when I start and end the pond. Of course, when I close it down depends on the fish that I've put in there. If goldfish / koi, sunfish, and Uruguayan cichlids were out, I would extend the closing date to mid-October or even later. The water temperature changes between day and night are much less than the air temperatures change since water retains heat much better than air. So if the daytime high were say 80 F, and the night time low were 50 F, the temperature of the pond water in my 1200G pond would only change by a couple of degrees over night, say from 75 to 72F. Of course, the larger the volume of water, the smaller the swings in water temperature. My Little Giant 'stock trough' pond (100G) on the other hand would cool down more like 75F to 65F for the same air temperature change. For a small pond, a heater might be advisable once cooler nights occur. Once the water temperature gets to the low 60s, especially for many of the more heat loving cichlids, that's about as low as I would want them to go. Adding a couple of high wattage heaters and covering the pond at night can extend things some. About 5 years ago, I had Longear sunfish, Gymnogeophagus gymnogenys, Australoheros sp. Red Ceibal, goldfish, and a foot long Pleco out until Nov. 2nd. the water temperature was 34F the air temperature 29F. All not only survived but looked magnificently colored when I pulled them out, icicles and all. Here is the temperature vs time graph, followed by a couple of pics of the fish as I was pulling them out in November (I don't wait this long any more ... too miserable shutting the pond down when it's freezing out).
