by Lane Lupin
(Toronto, Ontario Canada)
For years we used two de-icing machines to keep winter ice away from our cottage dock. Now a homemade bubbler does a better job, and uses less electricity too – a whole lot less.
My wife and I have a cottage with boathouse and separate dock 300 km north of Toronto. The huge forces created by the expansion of ice on the lake when the temperature falls below -10C plays havoc with lakeside structures such as docks and boathouses. For over twenty years we’d been using two de-icing machines. Such a machine consists of a half horsepower motor that turns an underwater propeller, causing warmer bottom water to rise to the surface, so as to prevent surface ice from forming. Since these machines run from November to April, the cost of power consumed can easily exceed $1000 per year. The machines must be installed each fall, and removed each spring for storage over the summer.
Another cottager found a solution which is equally effective, but which consumes only a third of the energy. We converted to this solution ten years ago, and so far are very pleased with it.
A long tube of copper pipe or PVC pond aeration tubing perforated with holes every 18″ – 24″ is placed along the lake bottom at the point where the water is to be kept open. A feeder tube with a check valve connects the lake bottom tubing with a 1/3 hp radial vane compressor mounted in the boathouse. The compressor is turned on by flipping a switch, and pumps air through the holes on the lake bottom tubing. The rising air brings up the warmer water from the bottom to the surface.
Since the power is only 1/3 of the previous requirement, and the area of water kept open is the same, we are pleased with the savings and extra convenience.
The bubbler system was fabricated and installed by a local company in Sundridge Ontario, called Near North Industrial.
(It will be necessary to compute the diameter and frequency of the perforations as a function of the tubing length and depth.)