Windmill Air Compressor Pumps

Windmill aerations systems are powered by the wind. As the wind rotates the blades (rotor head) – the compressor that is attached behind the rotor compresses air into an air-line. The amount of air that is compressed in the airline at the turbine height is much different as you go into the water and down to the air diffuser or diffusers that are placed in the deeper areas of the pond.

At the compressor height there is no back pressure so its quite easy for the blades to turn and the air to be compressed. The deeper you go into the water with air diffusers the more back pressure build up in the airline and the stronger the windmill compressor will need to pump in order to get air down to the diffusers that are in the pond. This is measured in PSI (pounds per square Inch) – the higher the PSI- the lower the air diffusers can be placed in a pond.
For every two feet of water that you go down-the compressor requires at least 1 PSI (pounds per square inch of pressure) to push the air down to the air diffuser.

For Example, Both Koenders Windmills and Superior Windmill have two models of air compressors. Dual Diaphragm Compressors and Single Diaphragm Compressors. According to their company engineers they engineered their Dual Diaphragm Compressors so that the diameter of the diaphragms would not change in size thus ensuring the strength, integrity of the entire windmill as well as the performance in lower wind speeds between 5-10 MPH.


All other vendors have single diaphragm models or a bellows pump model.


Koenders Engineers have stated that the design of the piston (diaphragm) to blade ratio is extremely important with respect to the overall integrity, performance and balance of the windmill aeration system.

They claim that “the theory of larger pistons produce more air” is flawed unless the power to drive the larger piston is provided. Power for windmills is translated into wind as a result the larger the diaphragm – the higher the wind speeds that are needed in order to drive the air compressor pumps. This will greatly reduce the amount of aeration and actual operating time of the windmill aeration system.

The other key factor that is in part related to the Diaphragm Sizing is the back pressure that occurs – the deeper you place the air diffusers in the water. (1 PSI pound per square inch of pressure is needed for every 2 Ft of water that you go down into the water) – Check with your vendors at what PSI of their air pumps -they range in the industry anywhere for 4-8 PSI right up to vendors like Koenders and Superior who’s air pumps compress air up to 30-35 PSI levels.

The larger the diaphragm diameter the greater the force placed on the connecting rods, bearing sets and other related components. We have designed our pistons to operate in all wind conditions while exerting the least amount of force on the other windmill components. Our track record for this design is proven.

Wind speeds is another key consideration- at what wind speeds will these compressors pump air into the pond and how much with they pump. The amount that these compressor will pump is measured in CFM (cubic feet per/min of air) -it’s important that this measurement be done at the diffuser level and not at the hub height.

The theory of “the larger the airline the better the aeration” is another theory that is considered flawed. Bigger airlines larger than 3/8th Inner Diameter have a negative impact on volume of air going directly into the water. You could put a 1/4 inch to a 3/8th inch airline on these windmills aerations systems and you would be much better off than if you were to place a 1/2 inch to 1 inch sized airline. The maximum airline diameter for maximum performance for all these models would be 3/8th .ID. Anything more than this will have an adverse relationship on the performance of the unit.

For example, the windmill has to produce more CFM of air to fill up the extra space in the airline before it will pressure up more volume of air to get oxygen into the water. Takes more time and more air to build that pressure up. That is why, to be fair we tested all units with the various diameters of airline and the most effective results for all units was 3/8th Inner Diameter. Remember this airline that we are describing is a special airline that does not expand under pressure. The airline that expands the least is the most effective for the aeration process. Ask your supplier if the airline expands.

Customer Feedback on Koenders Compressor Design

Koenders Windmills,

The Koenders Compressor has supported the aeration efforts for my fish pond since 1999. Due to the compressor’s high PSI levels I am able to attach two air stone diffusers to the one windmill and it has been extremely effective and reliable in aerating my 5 acre pond in Saint Jean Sur Richelieu, Quebec for almost 10 years. Here we experience cold winters and hot summers. The design has proven to work in both conditions. The only maintenance that I have done is a check valve kit for $20.00 that allows the air to be compressed in the airline and not leak out. The bearing sets that Koenders use seem to be of high quality – we have never had to replace any of the self sealed bearings.

Areas of my 5 acre fish pond remain open during the winter months so that my fish stay healthy and since installing our windmill we have never experienced a fish kill.

Koenders diaphragm and compressor design has proven to stand up to the test of time in all seasons. Great Job!

Yves Laliberte
Saint Jean Sur Richelieu, Quebec

Proven Compressor Design

I installed our Koenders Windmill over 15 years ago and can tell you that their design has proven to be extremely reliable and effective. The manufacturer recommends changing out a diaphragm replacement kit every 5-7 years (less than $ 50.00). Well it has been 15 years for me. Have never touched the windmill – we have simply greased the compressor base so that it swivels easier on the top of the tower.

We have a trout pond about 60 X 80 ft X 16 Ft deep so the windmill aeration has kept my fish from dying in the cold winter months. The aeration helps keep the algae and winds down as well in the hot summer.

In the winter I bring the air diffuser close to the edge of the pond so that I can keep an area of the pond open for deer to drink from at the edge of the pond.

If you have any questions just email me and I will try to answer them as best I can.

Ralph Welton
Economy, NS

Proven Compressor Design Provides Reliability

We installed a Koenders Windmill back in 1998 and all we did was hook the
airline up to the air diffuser that was provided and haven’t touched it since.

In the winter months the windmill aeration systems keeps a hole in the ice of
about 50 Ft in diameter. This ensures that health of the pond and our fish.
We have small and large mouth bass, cat fish, brook trout, blue gill, perch
and others in our pond and make sure they stay alive during the cold winter
months is a real key concern. The Koenders compressor pumps all year round,
in the extreme cold and in the hot temperature months of the summer.

I was surprised to hear that Koenders recommends that we clean the air
diffuser every few years and service the diaphragm every 5-7 years. Its now
10 years and we have not done one thing to this windmill.

We certainly would agree that the diaphragm and compressor is proven to work
on the Koenders Windmill.

Eric Faccia
Morgan, WI

Thank You for the Great Product

Our Koenders Windmill Aeration System has been working for 13 years straight and we have done absolutely nothing to it during this time. When you talk about proven product, components and compressors – I would have to believe that your product wins not only in your industry but for any other brand or product in any industry.

We have about a 1.5 acre pond 150 X by 300 feet with Bass, Blue Gill, Koi and Perch. It has kept our fish alive and healthy every year no matter how hot the summers get or cold the winters are. Our family uses the pond for both swimming and fishing. With the help of our Koenders Windmill aeration system the water has always been crystal clear. There are many ponds in our area and most visitors comment that we have the best maintained pond they have ever seen.

We have just ordered a replacement tank for our freeze control unit and a maintenance repair kit. Total order $ 60.00 US – I don’t need the maintenance kit yet but will keep it on hand. Manufacturer (Koenders Windmills Inc) has mentioned that the maintenance kit should last between 5-7 years – in our case its been 13 years and counting.

Gary Sansote
Bath, MI

Engineer’s Feedback From Canada

I am an engineer and have been using a Koenders Windmill aeration kit for over
8 years. The engineering behind this unit is simple and smart and am very
impressed with the efficiency and reliability of its design.

We have a long pond about 800 Ft and without the aeration from this windmill
unit it would virtually be impossible to control algae and weeds in our pond.

When we first designed this fish pond it filled up in four days and has been a
joy to have on our land. Thanks to Koenders it has made managing and
maintaining are pond easy and affordable.


David Sadleir
Rosemont, Ontario

Koenders Windmils Design Built to Last

Our Koenders Windmill has been an excellent functioning product for 18 years. We have a 100 X 200 Ft dugout full of brook and rainbow trout.

The dugout water is also used for toilets, washing clothes and dishes, showers etc.. for the farm house. Before we put our windmill up the pond looked like a slew – after a few months it started looking like a fresh lake and has been doing so ever since.

The design of this windmill is incredible. It works in low winds and is designed to last decades, just as Koenders Windmills promises.

We also use the windmill to keep our fish healthy during the winter months and we fish during this season as well. The windmill and the pond has given us years of fun.


Mervin Arstall
Saskatoon, SK