Pond Heaters

We had a good freeze last week, ended up with ice across my entire pond
except 1) where the water falls from the bio filter and 2) the skimmer.

Question is this. In order to be prepared for the next freeze (spring ain't
here yet) I'm wondering what type of heater (or bubbler) I should install.
Y'see I have an 11' x 16' pond, about 24" deep at the deep end. Seven
Comets and one Koi in the pond as of last spring, but I haven't seen them
for nearly two months. I expect they're hiding in the hidey holes built by
all the rocks that line the pond.

Suggestions?

--
~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=

john burton
Bach 50B3
Bass Trombone, Charleston NeoPhonic Orchestra
South Charleston, West Virginia