• Practical Information
• Industry Glossary

CONTROL OF MILFOIL

CONTROL OF MILFOIL

 

CONTROL OF MILFOIL
BY COMBINING
           AERATION, WATER CIRCULATION, BACTERIA

CANADIAN POND AERATION SYSTEMS are made up of:

-A Compressor powered by electricity, windmill, or solar power
-An aeration device; either an Air-Station, usually made up of 2 or 4 individual diffusers or Bubble Tubing which is a length of self sinking tubing that diffuses bubbles.
-Weighted tubing carrying compressed air to the aeration devices.

Such Aeration System will emit thousands of tiny air bubbles which will rise to surface pulling a column of water up with them. While adding much needed oxygen, this system will create a laminar flow of water. Gallons per minutes of water moved are in direct relation to the depth and type of device used. The result is well oxygenated water circulating through a Milfoil Bed. Once aerated and circulated, beneficial Bacteria should be added to the – reason to follow.

A System must be designed to the specific needs of each location allowing for individual conditions such as:

- Density of Milfoil growth
- Size of area to be cleared
- Lake Bottom condition – bottoms of Milfoil Beds are usually made up of decaying organic matter - silty and mucky.
- Water depth

Lets look at an example of a typical System. Assume we have a cottage with a Milfoil bed spread across its waterfront – the bed is 60 ft. along the shoreline and extends out into the lake 60 ft.- total 3,600 sq. ft. The Milfoil growth is dense; the bottom is heavily silted; and water depth averages 10 ft. This probably would require 4 Air Diffuser Stations (2 discs model) each providing 3.000 gallon of circulation per minute for a total of 12,000 gallons of water now well oxygenated and spreading throughout the Bed. Cost of the system would be in the area of $2500. If self installed [installation is easy]. Bacteria costs would be on top of this. Also keep in mind 3,600 sq. ft. is a large area and probably greater than many cottagers would have to clear.

HOW DOES THIS SYSTEM WORK

Milfoil requires an abundant supply of Lake Nutrients or it perishes. Fundamentally the System operates by STARVING the Milfoil of Nutrients. It does this in several ways:

-Circulating water attracts and holds some of the Lake Nutrients in the circulating water, thus tending to deprive the Milfoil of some of its normal food availability.
-Well oxygenated water acts to oxidize the bottom silt so there is not the usual release of Nutrients. Silt has a heavy content of Nutrients
-The decaying process of the bottom silt is accelerated by the addition of more Bacteria, and Oxygen combining with the Nutrients already there to hasten the decomposition process but also to further reduce the silt content.
-As the Milfoil thins out, other water plants which were crowded out by the aggressive growth of the Milfoil and its ability to restrict vital sun rays to these other plants through Milfoil`s extensive surface mat, start to reappear and fight for what Nutrients are still available.

The annual Milfoil growth cycle starts in the Spring / early Summer as the water starts to warm. Growth as most of us well know is rapid and extensive through the Summer and early Fall. Eventually stems and surface mats die leaving the roots to survive Winter and provide new growth in the Spring. Circulating and Aeration extend the Fall life of the tops and leave the roots less able to survive the long freeze up period.

A word of warning - the Milfoil Eradication Program described above is not instantaneous. It can be very substantial very quickly, or it may take longer than one season to do the job. We do, however, have glowing testimonials on its ultimate success.

Apart from its possible slowness there are compensating advantages to the deployment of the Aeration, Water Circulation, and Bacteria approach. Just a few would be:

-The cost of buying and operating the System is not great when you consider the benefits – being able to swim in front of the cottage and back the boat out without having to pull up the motor to clear the propeller of the tangled Milfoil weeds. My system cost $2,500, Bacteria included. Hydro costs will be about $15 per month for the approximate 9 month a year it will operate
-Ongoing control efforts are easy. Once you have cleared your area the system will keep it clear even if Milfoil remains in your bay or vicinity.
- Many other eradication methods are labor intensive and never ending. Like mowing grass it comes back in a few weeks, and again, and again, both this year and next. - System maintenance is easy; to start in the Spring plug in the Compressor and open 3 valves, reversing this process in December. You can not operate the system once ice starts to form because you will have, with aeration, an area of open water or weak ice very hazardous to surface traffic such as ATVs, Snowmobiles, etc.

The process is Lake Friendly. It returns, albeit a small part of the lake, from its Eutrophic state [rich in Nutrients supporting abundant plant growth including Milfoil and Algae] to an Oligotrophic state [rich in Oxygen and scarce plant growth] – the type of conditions normally found in a lake with a steep rocky shoreline and clear deep water.

If you have questions about the foregoing, or about alternate approaches to eradication, or wish to talk about a system for your cottage and get a specific quote give us a call.

Bill Henderson, Canadian Pond Customer & Representative
info@canadianpond.ca