strange dock circulator issue

[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.