Any sized hole will work - mine is currently ~ 5" with an airstone - the
point of the hole is to allow air exchange so toxic gases don't build up,
trapped beneath the ice
Gale :~)
"Don Cunningham" wrote in message
...
I use a stock tank heater to maintain a hole in the ice on my pond. My
question is how large a hole is required?
I have a 1200 gallon pond. My heater is 1000 watts and keeps about a four
inch hole in the ice.

don cunningham