Question
Hi my name is Dale Watkins. I have a 2500 gallon pond with 6 Koi, 3 Catfish, 3
snails, and 2 goldfish. I am getting a pond heater for this winter. My question is
what temp should I set the temperature? I live in Chambersburg, Pennsylvania.
Also, should I keep my waterfall running until spring?

Answer
If the heater has a temperature setting, you can either simply set it to prevent the pond from freezing at say 34 or 35 degrees F, or you can set it higher if you really want the pond warm and the fish active.  Depending on the heater, it may not be able to warm it up too much.  Also, it will be extremely expensive to heat it more than a few degrees above the air temperature.  Making an enclosure over the pond can warm things up.  Some rich koi keepers have heated water running under their ponds that keeps the pond at 55 degrees F all year so they can always feed their fish.  The fish then don't hibernate.  I suggest keeping the pond simply slightly above freezing so it doesn't completely freeze over.

Like many people, I have a de-icer which has no temperature control.  It kicks in when it's near freezing and leaves just a small hole when it's really cold.  

I live in central MD and leave my waterfall going all year.  To read about the pros and cons of leaving the waterfall going as well as de-icers and other winter tips, see my web site at http://www.fishpondinfo.com/winter.htm

Good luck!