wrote:

should I get a top floating heater or a submersible heater?

Normally I wouldn't recommend heaters, but Jan's right (if you're really
zone 4/5 - I used to live on the other side of lake Erie, and we were zone
5/6 - I would have thought you'd be no colder and get better protection
from snow cover). So submersibles are the best way to go. Floating
heaters just radiate a lot of the heat straight into the air. Derek

And with the above in mind, another thing you could do is cover the pond
similar to what I have shown on my website. Boards supporting screen door
or shade cloth ~ 6" above the surface of the water. When you get snow it
traps the heat and makes an igloo affect. This is when wireless submersible
thermometers come in handy. ;o) ~ jan


See my ponds and filter design:
www.jjspond.us

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
To e-mail see website