strange dock circulator issue

[winterh]

I have 3 separate circulators positioned around my large L shaped dock all controlled by a thermostat timer. Have run like this for many years and never an issue. Something strange yesterday and I don't understand how its even possible. They have not been running because I do not turn on till I get ice. I now have ice and turned them on. The breaker tripped and when I went to investigate 2 of the 3 were encased in a block of ice. How is that possible when they are in water about 5 feet deep? The ice bound the propellors which I assume tripped the breaker. Lifted them out, broke up the ice and they worked again. I have never seen ice form on the bottom before.

[livinthedream]

Are you in an area with little or no water movement? Even with that 5' of ice seems crazy.

[TomC]

I don't think he is saying the ice was 5 feet thick, but rather the circulators were ice encrusted at a depth of 5 feet under water. Perhaps I am wrong, but that is how I interpreted his description...

[winterh]

Yes, I mean they were encrusted with ice at a depth of 5 ft. The top ice was only about 4 inches thick. When I say encrusted it was not a solid block of hard ice. More like a very compacted slush. When I pulled from water I banged the circulator on dock and it fell off. I have never seen or heard of ice of any kind forming near the bottom. Especially enough that it surrounded my propeller and made it unable to spin.

[fatlazyless]

So, the water is 33 to 34 degrees and is windy, wavy, while the air temp is maybe 13-degrees and you wonder why did the water become ice within the water aerator and stop the movement of the small blue plastic propeller?

Is because the 110-volt electric line is copper and it conducts enough cold temperature down to the aerator motor so the water will freeze close to the aerator which conducts the cold temp to the water, nearby. ...... ..... this is why!

[DickR]

The only thing I can think of, admittedly getting creative here, is that the recent strong winds, combined with a lot of open water upwind of the docks, pushed a huge mass of broken ice ashore, to the point of piling up multiple feet in height. Over time, water motion would disperse the loose ice mountain and the chunks would rise away from the shore. Any other wild ideas?

[John Mercier]

I was thinking something in the water got on the bubblers and the ice formed around that.
Sort of like seeding clouds to get it to rain.

Just can't think of anything that would be in the water to cause ice to form like that. An algae or maybe the aluminum sulfate they used to fight the CB?

[winterh]

Originally Posted by DickR

The only thing I can think of, admittedly getting creative here, is that the recent strong winds, combined with a lot of open water upwind of the docks, pushed a huge mass of broken ice ashore, to the point of piling up multiple feet in height. Over time, water motion would disperse the loose ice mountain and the chunks would rise away from the shore. Any other wild ideas?

Thats what I was thinking I am in south Wolfeboro bay and the ice that formed there over last few days was all small unconnected pieces that were floated in by the wind. I could see how they could pile up against the dock and circulator all the way to the bottom getting slushier as they went deeper. That would explain the consistency of ice that surrounded it too.

[GTO]

Originally Posted by winterh

I have 3 separate circulators positioned around my large L shaped dock all controlled by a thermostat timer. Have run like this for many years and never an issue. Something strange yesterday and I don't understand how its even possible. They have not been running because I do not turn on till I get ice. I now have ice and turned them on. The breaker tripped and when I went to investigate 2 of the 3 were encased in a block of ice. How is that possible when they are in water about 5 feet deep? The ice bound the propellors which I assume tripped the breaker. Lifted them out, broke up the ice and they worked again. I have never seen ice form on the bottom before.

This was sent to us by Watermark who service out dock and circulators:


Unprecedented strong winds over almost an entire week has broken-up much of the ice in larger bays and unprotected waters. The northerly winds, and subsequent constant wave action, has pushed large amounts of floe ice into shorelines facing generally north. As the ice floes hit shore, they break-up into smaller pieces and as the winds were sustained over the week, the “chunks” stack-up and can essentially freeze the water solid from the surface to the lake bottom, even in 4 to 5 feet of water!

Combined with the above, we are experiencing some of the lowest water levels we’ve ever seen. For example, in late fall the water levels on Lake Winnipesaukee were 26 inches (+) below Full Lake Level!

This means that many ice circulators are “frozen-in” and many have been damaged due to the ice pressures, mostly solid in the water column, where they are located. And, in many cases, the low water levels mean your circular is not operating in the most efficient manner. This is not the “normal” situation bubblers are designed for and there is simply no way to get the unit operational until the ice conditions change. Fortunately, it looks like we’ll have some seasonally “warm” weather this week.

[dippasan]

I've used a circulator for 12 years to keep my "U" shaped dock open. I've always been amazed at what a great job it does keeping ice from building up on both docks .
This year....not so much.

I check my camera several time's/week and so far the circulator has only kept approx 10x10' area open in between the docks. the docks themselves are encased in ice. I feel it's due to the extremely low water level and colder than usual temps. As you may know, circulators basically work by circulating warmer water from the bottom to the surface. It may be that water temps at depth are not that much warmer because of the lower lake levels. (My own opinion/explanation)

The circ is on a timer and runs every day from 5pm-7am.

Your thoughts are welcome

[Descant]

Can it be controlled by a thermostat instead of a timer? If temps are lower, as you suggest, maybe two hours per day isn't enough?

[DickR]

Originally Posted by dippasan

...
The circ is on a timer and runs every day from 5pm-7am.

I don't think fourteen hours in one long ON shot, then 10 hours totally OFF is an optimum strategy at all. One certainly can argue that the normally colder night time hours could benefit from more ON time than would daytime operation. But bear in mind that once circulator operation has cleared ice sufficiently well from the dock, continued circulation is just a waste of power. On the other hand, long OFF intervals in really bitter cold weather can result in formation of significant ice thickness. In shallow water, this could really impact movement of water during ON time and thus impede remelting.

Another down side to very long ON intervals is that an even greater mass of water gets set into motion, which results in melting of a lot more of shoreline ice to either side, possibly affecting abutting properties. State law does say that operation of a circulator should not keep an abutter from accessing the lake ice from shore.

My own feeling is that, in most cases, a better strategy is having a lot of reasonably short ON intervals, spread more around the clock, perhaps favoring the colder night time hours. Not a lot of ice can form in the shorter OFF intervals.

[dippasan]

Originally Posted by DickR

I don't think fourteen hours in one long ON shot, then 10 hours totally OFF is an optimum strategy at all. One certainly can argue that the normally colder night time hours could benefit from more ON time than would daytime operation. But bear in mind that once circulator operation has cleared ice sufficiently well from the dock, continued circulation is just a waste of power. On the other hand, long OFF intervals in really bitter cold weather can result in formation of significant ice thickness. In shallow water, this could really impact movement of water during ON time and thus impede remelting.

Another down side to very long ON intervals is that an even greater mass of water gets set into motion, which results in melting of a lot more of shoreline ice to either side, possibly affecting abutting properties. State law does say that operation of a circulator should not keep an abutter from accessing the lake ice from shore.

My own feeling is that, in most cases, a better strategy is having a lot of reasonably short ON intervals, spread more around the clock, perhaps favoring the colder night time hours. Not a lot of ice can form in the shorter OFF intervals.

Thanks for the reply.
Instructions with the circulator actually recommend longer "on times" instead of shorter on/off cycles and I have never had a problem in the past. My abutting neighbors have circulators as well and are snow birds so no concern about their need for access. Plus I'm in contact with all of them all winter. I also have a thermostatically controlled timer that stopped working. I have since repaired it and will put it back in service when I can get across on the ice, perhaps very soon.