Just noticed this posting. For the OP, I'm pretty much in the same area you are.
2'9" is not much off of 3'. I wouldn't be too worried. But it sounds like you are already moving them in.
We have an 3'11" pond. We use a bubbler that is about 6" below the surface and we place a 1500W stock heater over it but we don't plug it in. We only plug it in if it gets so cold that the bubbler fails to keep a hole in the ice. Once the stock heater is frozen in the ice for more than 2-3 days we plug it in and let it do it's thing than we unplug it. Usually by then the cold snap is over and the bubbler is sufficent again. If not, we plug it back in again 2-3 days after the next freeze over.
8-10" would be about the thickest ice to ever expect in this area. And that would be extremely unusual. At least 4" is required to ice skate on ponds and most local townships that allwo public skating in government owned parks require 6".
Here's Minnesota recommended guidelines for ice activities: http://www.dnr.state.mn.us/safety/ice/thickness.html
It's been a rare instance in the past 20 years when we could ice skate on local ponds in the Philly region.
Of course the depth of the water freezing is also influenced by the pond design.
But I think you are generally safe at 2' 9". AS an experiment you might want to get a wireliess thermometer and put the probe in the bottom of the pond for the winter and see exactly how cold it does get during the winter.
Craig
2'9" is not much off of 3'. I wouldn't be too worried. But it sounds like you are already moving them in.
We have an 3'11" pond. We use a bubbler that is about 6" below the surface and we place a 1500W stock heater over it but we don't plug it in. We only plug it in if it gets so cold that the bubbler fails to keep a hole in the ice. Once the stock heater is frozen in the ice for more than 2-3 days we plug it in and let it do it's thing than we unplug it. Usually by then the cold snap is over and the bubbler is sufficent again. If not, we plug it back in again 2-3 days after the next freeze over.
8-10" would be about the thickest ice to ever expect in this area. And that would be extremely unusual. At least 4" is required to ice skate on ponds and most local townships that allwo public skating in government owned parks require 6".
Here's Minnesota recommended guidelines for ice activities: http://www.dnr.state.mn.us/safety/ice/thickness.html
It's been a rare instance in the past 20 years when we could ice skate on local ponds in the Philly region.
Of course the depth of the water freezing is also influenced by the pond design.
But I think you are generally safe at 2' 9". AS an experiment you might want to get a wireliess thermometer and put the probe in the bottom of the pond for the winter and see exactly how cold it does get during the winter.
Craig