During January and February of 2019 temps in Waukesha County, WI reached -20 degrees 2x. But this little hearty device kept the pond open enough so the fish survived.
De-Ice to - 20 degrees
Testimonial - "This is the first year in five winters that our fish stayed alive in our coy pond. I am very happy we had the PlasmaE Pearl De-icer when temps were below zero for multiple days in a row, several times this winter." - C. White (3/19)
De-Ice to - 20°