Zfishies;4102294; said:
What was it in the middle of December & January? When the nights were longest and coldest... and the daytime temps were lowest with the least amount of sun?
I do believe the unit you linked above will help get you at or closer to the 70*F mark in spring and fall... but not in winter...
The size (surface area) and depth of your pond will also make a big difference. Most of the heat exchange (loss) occurs at the surface, so the less surface you have and the more depth you have the less heat loss you will experience.
My suggestion is to set it up and monitor it for a full year to gain insight about the practical reailty before stocking it with temperature sensative fish.
