Whenever I go to visit a pond in need of help I am always asked of the effectiveness of windmill aeration systems to supply the circulation and oxygenation needed to restore a pond that is full of stinky muck and sludge or feeling the common problems of thick algae growth on the surface. Of course an electric aeration system might be more efficient in the end there is still the idea that a windmill could assist in beneficial ways and as such would require no costs beyond the initial installation and proper anchoring of the windmill. The idea is sound and understandable with the cost of operating an aerator but sometimes a windmill is not all it is cracked up to be despite the best marketing points of dealers and the manufacturers of these devices.

First, before I get into my windmill ratings of the different options available on the market, let me try and describe the operation of the typical windmill system and how the homemade aeration aficionado may have a lot to realize before embarking on a new project such as trying to build a do-it-yourself windmill aeration system.

The windmill tower
Most windmills built and sold in North America are constructed in a similar fashion and before I give my ratings for the different approaches for anchoring and construction I will start with the basic step by step approach. The tower of the windmill must be strong enough to withstand severe winds and pond owners often underestimate the ability of their clay or soil to properly anchor the steel anchoring pins included with most kits. For the last 20 odd years the principle style of windmill tower has been a three-legged twenty foot structure made of galvanized metal. The average footprint of a 20 foot windmill is between 84 and 100 inches depending on the precise model being purchased. There are similarities between the models so ensure than the retailer offers the precise distance for the anchoring pins especially if you want to anchor them into cement footing prior to erecting the windmill tower. I have seen some poor souls anchor their pins in 12 inch diameter sonotubes only to discover that their footings were off center by 2 inches and the results were not pretty! The three-legged windmill tower has been popularized by the Koenders and Superior brand of windmills.

There are also four legged windmills such as the Beckermills Windmills or the American Eagle Windmills which requires a square based footprint of various sizes depending on which height is chosen. . I find that it is best to but the tallest windmill that will fit your budget and your landscape; the higher tower allows the windmill head, fan blades, to capture as much wind as possible. While manufacturers claim that their mills will operate in as little as 5 mph I tend to err on the side of caution and suggest that it is best to buy the tallest windmill that will fit and expect that the wind required is as much as double to what is reported!

A new arrival on the scene is the uni-pole or single pole mount windmill. Until now I've seen many people mount the head of a windmill on a number of structures from old radio towers to telephone poles with limiting degrees of success. The single pole can be aesthetically more appealing to many pond owners who find that next to their pond the three or four legged structure appears either too old-fashioned or too much like a power company or cellphone broadcast tower! The new 25 foot tall single uni-pole windmill has the advantage of being able to enter into zones of higher wind speeds which is critical especially when dual-diaphragm compressors are used to aerate larger ponds with a windmill. One nice thing about a unipole windmill is that the footprint of the structure is much smaller than a three or four legged windmill although it does require a solid slab of approximately 10 by 10 feet to be secure. The aluminum reinforced pole is similar to a lighting mast and usually comes with a hinged base or pivot points like the multi-legged models to make erection and servicing off the windmill easier. The taller structure definitely puts the fan blades up where the swifter winds blow; I've seen a unit mounted on a 40 foot tower and that sucker really never stopped spinning there was so much constant wind. Of course mounting the compressor on build your own windmill type towers makes servicing or changing parts difficult so may be only an option for farmers or owners of machinery or tractors or cranes to to help with the installation.

The windmill air compressor system
Most windmills sold in North America, besides the ones that generate electricity, are diaphragm pumps. Anyone familiar with the simplicity of an old-fashioned pump understands that this is likely the main reason for the absolute success in efficiency of a windmill aeration system. These compressors can deliver anywhere from 6 to 30 psi depending on the make and model chosen which make them serious competition to such renewable energy opponents as the solar power systems which typically generate less than 5 psi for a similarly priced system. An expensive windmill will still be much cheaper than an inexpensive solar system so I often recommend to my clients to consider wind power over solar power. There are a few configurations available on the market today and anyone visiting a pond supply store should understand the needs of their pond versus the realistic performance parameters of the windmill; be sure the company you buy from offers the expertise and preferably the local windmill installation service as the building of a windmill plus the installation of airstones can consume several days for a novice and due to the complexity of the systems, despite the detailed instructions that typically come with the product, the final cost in time alone can make it a better deal to hire the experts to build and install the system. When my team does a complete building a windmill and installing a windmill package we usually charge $1500 so even though you are buying a windmill on Ebay you must realize that there will be additional costs!

Let me get back to the diaphragm: typically a sheer rubber circular piece of heavy duty flexible composite material creates a seal on the pump head and as the blades or fans of the windmill turn it pulls and pushes the diaphragm and the sealed chamber builds up pressure and pumps it down an airline towards the diffuser, airstone or diffuser tubing in the pond. Because the high pressure capacity of the windmill you can run a tubing length of up to several hundred feet and your diffuser can be placed in a depth of over 20 feet.

The windmill diaphragm is the one thing we see wear out after a few years of service but there are windmill repair kits available for all models sold and the replacement of these parts is as easy as opening the hatch in the windmill head and removing the worn parts and replacing them with the crisp black diaphragms. To perform this windmill maintenance it requires the tower is lowered to be able to open and adjust the windmill head and this is another reason why hinged anchor braces or pivot pairs should be used.


Windmill diffusers or airstones
Most windmill aeration pond systems come complete from the pond store with everything needed to get setup and, within a few days, have your pond being aerated but it is very important to understand what is needed as far as tubing, air diffusers and clamps and connectors to be sure that when you leave the pond supply store that you are not going to be in for a surprise!

The standard airstone diffuser offered with most windmill systems have been around for decades and are simply a porous stone that allows compressed air to be forced up through the material which diffuses the compressed air and releases thousands of tiny air bubbles of very small diameter. Small bubbles are much better for aeration and circulation as the rising mass of small bubbles creates a large concentrated area of rising waters that pull a large number of gallons per minute of water to the surface. The deeper you have your airstone the more movement can be created.

Diffuser aerstones have a footvalve on them which a acts as a check valve so water does not get into the airline and restrict the air. Even though the compressor develops up to 30 PSI the effectiveness can be greatly reduced if water is clogging the lines.

There are a number of membrane diffuser discs available, some come standard or as an optional purchase. There are benefits to using membrane diffuser discs but there is no rule of thumb that states they are preferable. The determining factor when buying a windmill is not whether it has an airstone or a disc but rather what is the cost of the whole package especially when there are only a few windmill companies in Canada and the USA namely BeckerMills, Koenders Windmills, Superior Windmills and the American Eagle Windmills.

There are also diffuser airlines available that can be used but I don't have enough experience with bubble tubing type systems to know if they perform as well as a diffuser or airstone. Because this sort of weighted bubble tubing requires fairly constant depths and the windmill systems send pulses of air instead of continuous flow I could see the potential for the bubble tubing only working to full potential of shorter lengths were used like 25 to 50 feet.

Windmill water pumps can also be added to almost any free air windmill. They do have limits though and typical have a maximum lift or head of only 40 feet and then will pump less than 3 gallons per minute; but a water pump can be added if you need to.

Windmill compressors: the heart of the system
Without question the most important component of any windmill system is the actual air compressor and the drive system that is turned by the fan blades in the head. There are single diaphragm compressors that create a blast of air on every full-turn of the fan and there are double diaphragm compressors that send a stroke of air on every half turn. The double diaphragm units can thus create double the CFM movement as a single. Typical specs of any windmill provide an airflow range of between 1.5 CFM and 3.2 CFM. Calculating the actual output of CFM is not easy with a windmill because the wind is constantly changing slightly so it is rare than any mill will be providing a constant CFM rate for longer than a few seconds before the rate changes to to minute fluctuations in the wind speed and direction.

The diaphragm itself is usually made of a neoprene flexible composite which is attached to a precision machined diaphragm push plate. This is the one replacement part that will need to be changed eventually. The diaphragm replacement kits are fairly cheap and it would be a good idea to keep one on hand just in case.

The driving force of the system will be the wind so the size of the fan blades will determining how much air can be pumped. Naturally, the best place for your tower is where there will be constant or at least generous wind. The full sized windmills have a fan diameter from 65 to 72 inches and some of the new backyard windmills have a 27 inch fan. Almost all windmills have 12 fan blades. The largest blades are available on the Beckermills Windmills and the American Eagle with a size of 6 feet. This extra few inches can make a huge difference in torque and startup speed and the oversized diaphragm of the Beckermills system delivers up to 60% more air than a Koenders model, but again that is difficult to measure but sure sounds good to me!

Windmill Reviews
All reviews are based on our knowledge and should be considered as opinions and not scientific or even valid in some cases. May the buyer beware in all cases and ask questions before you buy! Windmill manufacturers are welcome to submit their product information or windmill plans to us.

In my years in helping solve pond issues I have seen my share of windmill projects. We now sell some quality windmills through our new retail arm of The Pond Report; previousely our policy had been to leave the shopping to those with the hard earned money, but our clients requested that we sell the products that we believed in so we have now begun offering our readers the ability to buy through us and to recieve excellant price points as we deal directly with some manufacturers.

This is our way of monetizing The Pond Report instead of just providing free links and reviews of products, while that may help manufacturers, it does little to send our kids through college.

There are so many options when it comes to windmill airiation that it is crucial to use due diligence and to look for the best deal. But beware, the best deal isn't always the cheapest. I have seen some people save a few hundred dollars by buying a windmill on eBay but then they got no service or tech support when things go wrong. My advice has always been: deal with a company that does more than sell pond supplies; make sure they have an actual store, with employees and a track record of knowing what they are doing. There is more to doing the right thing than saving a few dollars; getting good advice and information is worth much more in the long run.

Outdoor Water Solutions
Outdoor Water Solutions recently began manufacturing a product line of aerating windmills. We have yet to test the windmills from OWS so if anyone has feedback or information on ther purchase please email it to us. If anyone has actually bought one of the OWS Mills and would like to share their windmill building plans and experiences then please contact us.!
Pond Report Product Quality Rating™ : ?/10

Beckermills Windmills
The Beckermills system is a sturdy four legged tower and boasts the largest diaphragm and large fan blades precision engineered to operate at lower wind speeds and allowing the single unit to deliver over 3.2 CFM. The highest air output of any single diaphragm model. Available in 12, 16 and 20 foot models and also an impressive array of colors these mills have never ceased to impress the owners who buy them. Very good quality windmill, made in the USA, with a three year warranty. Head office in Wapakoneta, Ohio and no office found in Canada means most owners of these mills are in the USA.
Pond Report Product Quality Rating™ : 8/10

Superior Windmills
Another three legged system available in 4 sizes, 12',16, 20 and 24'; with Jetstream and Turbo Jetstream options. Superior windmills is based in Saskatchewan Canada, and is a serious competitor to Koenders Windmills. We have heard many customers who bought the Superior models complain about the lack of customer service and the poor quality of the merchandise. We've had phone calls even in July 2008 where clients were unsatisfied with the poor quality of the windmills...the company sens out press releases about how they are doing better yet still...the customers have the last word!
Quality issues dogged the company in its early days but since manufacture reverted back to Saskatchewan, the quality has improved dramatically and they now offer excellent value for money Several years ago Superior Windmills designed a dual diaphragm compressor and now hold a patent on this technology. So successful is this design, that the market leader Koenders Windmills uses this product under licence in all its dual diaphragm models. Many of the design strengths of Koenders are featured in the Superior range, which is not surprising as they both share many of the same manufacturing specifications and processes.
Pond Report Product Quality Rating™ : 4/10

American Eagle Windmills Made in the USA.
The American Eagle bellows windmill is a high-volume low-pressure aeration windmill. The bellows type of compressor delivers from 3 to 6 CFM with a maximum 8 PSI which means your diffuser airstones should not be in waters deeper than 15 feet. The Manufacturer recommends 12 foot placement of diffusers.

The American Eagle is another impressive four legged tower that comes in 18 foot and 23 foot towers and has a large 6 foot diameter fan head. They use a bellows type air compressor of Goodyear quality and the warranty on the bellows, the most important part, is 5 years which is the longest warranty of any manufacturer.

The American Eagle Windmills now have Zinc Plate/Yellow Chromate Crankshafts.

The original crankshafts have been field tested for over 3 years now; therefore much longer warranties will come into effect soon. They field test hundreds of units prior to giving unrealistic warranties. We will keep you posted of any new American Eagle developments.

Pond Report Product Quality Rating™ : 8/10
See pricing on American Eagle Windmill packages

Koenders Windmills Made in Canada.
The diaphragm system of the Koenders compressors can deliver up to 30PSI which is great for deep water performance and is many times higher than the American Eagle. CFM ranges from 1.5 to 3CFM depending on if you have a single or dual diaphragm model.

Koenders windmills have been in the windmill business for years and theyhey have three tower heights to choose fro: 12, 16 and 20 and new 24 foot tall tower towers (all with three legs) and they have a sleek and modern windmill the 25 foot high Uni-Pole Windmill Aeration System. Their Single Disphragm Pump Compressor produces up to 1.5 CFM and the double pump compressor produces up to 3 CFM. Their comprehensive warranty is a solid three years on the their windmills.

Their continuing efforts to improve quality have paid off, especially for consumers who want a quality aerating windmill, and in the newer Windmill Installation Manuals they reference to the offset hole technology they use which adds to the overall strength of the structure. Having to use tapered alignment punches and needle nose vice grips slows down the assembly but it adds to the strength enormously; some competitors use slotted holes to overcome this perceived ‘problem’ but when a nut comes loose then the strength is lost completely. The strength of any windmill is one of the keys to safety and longevity and Koenders Windmills have, through their years of product development, produced some of the best inovations in windmill technology that competitors often try to imitate.

Fairly easy to build, a DVD is included in their kits, but watch the barbs on the metal when building the unit; gloves are recommended and handy gloves are sold by Koenders. They claim that the single pump head is suitable for up to 2 acre ponds and the deeper the aisrtone the more acreage you can airiate with a windmill.

Koenders windmills have been icons of top quality so people wanting to buy a quality Made in Canada windmill should look no further. The quality in Koenders has been proven again and again by thousands of satisfied customers. Head offices in Regina, Canada means decent service anywhere in North America as they ship their mills from their central location very quickly.
Pond Report Product Quality Rating™ : 8/10


Using a windmill for aeration is often the only choice for isolated pond owners or farm dugouts. Not to mention the fact that no wires or electricity payments are required it makes it a good option worth investigating.

Another reason many of my clients have decided to use a windmill versus a solar system or the standard electrical aerator is because it is simply more organic! That's right, think about it...nature is full of ebbs and flows, nothing is constant! We have day and night, warm days and cold days, windy days and calm days, rest and action. The windmill fits perfectly into this naturalistic and holistic approach. There are days when the pond is calm because there is no wind and no bubbles...and other days when the winds create conditions for the windmill to turn and the pond is bubbling. Doesn't this seem like it is how aeration should be? Instead of a constant bubbling churning like a washing machine the pond can go through phases of calm and action.

To me using this philosophy makes the most sense and is why windmills are one of my favorite ways of aerating without electricity.