Hi, Can anyone on here confirm or deny Koenders claim of 3 CFM in 5 mph winds? Thanks!

I have a Koenders double diaphragm unit and I seriously doubt it does that much.

It is probably possible for the Koenders windmill to create some air volume maybe 3cfm with a 5mph wind. However this will only happen when the diffuser is in very shallow water or in no water thus no head pressure is required. Thus the statement is not a complete lie. This is because the air pressure needed is a lot less in real shallow water compared to a diffuser set in 10-12 ft or deeper water. Wind speed determines how much pressure the windmill diaphragm can create. The stronger the wind and faster the wheel turns the more psi it can create and the deeper the windmill can push air. Then as the wind speed increases more air volume is created and increases and more bubbles occur due to a 'harder' pumping action.. So the deeper you set the diffuser the more wind speed is needed to get enough pressure to release a little air at that depth; more speed then adds more air. Pressure needed rule is - 0.5psi for each one foot of water depth. 1ft depth requires 0.5psi = "easy peasy". 5ft depth requires 2.5psi and 12ft depth requires 6psi, and 20ft depth requires 10psi. Also note that as the diaphragm ages and gets 'weak' and stretched or cracked the more wind speed is needed to generate the same pressure as a new diaphragm. I like the electric air compressor because it always or constantly produces lots of air volume at most all depths although it also has its limits based on the type of compressor and psi ability at each depth.

It would be very interesting to see a pump curve on their system/s as it would have a windmill speed "twist" (pun??? - lol) that we do not see with the constant RPM electrical ones that are most common. The correlation between wind speed, psi, and CFM would help confirm Bill's comments (which I concur with, btw).

If you are considering buying one, please request a pump curve that correlates wind speeds from them and we can talk nerdy aeration pumps for a bit.

I doubt it. Their single diaphragm system is rated at 1 CFM.

The other thing that limits their CFM is that they furnish the system with 3/8" airline.

Here is a windspeed to CFm ratio chart from OWS. But that is what Koenders main claim is. That they can produce 3 CFM at very low wind speeds. So, overall you should get more air movement.

The reason I asked about windmills is that I don't have a power source and the solar setup I would need to run these plug-in units is insane.

What unit is this pump curve for? It shows about 3/4 CFM at 5 mph and a maximum output of 3.5-4.5 CFM at 25 mph. Using the average wind speed for Rimbey, Canada (8.2 mph), this pump curve shows it would be putting out about 1.3 CFM of air at a diffuser depth of 5 feet.

In my opinion, this type of average flow is adequate for a single diffuser. Two diffusers would work if desired, but the total flow and turnover rate would likely suffer, some, due to added overall line lengths and I would stay away from that. Either way, you are relying on the wind and pond turnovers would obviously change with the wind speeds from day to day. Given your situation (no power and the desire for aeration) The unit depicted by the curve would be best suited for a small pond around a 1/2 a million gallons (1/4 acre, 10 foot deep - thereabouts) with one diffuser at a depth of 5 feet. This has been calculated using an average wind speed of the 8 mph, a 1/2 million gallon pond, a Vertex 9" diffuser @ 5', minimal line lengths (preferably 5/8 id line, not 3/8"), and turning the pond over twice in a 24 hour period...assuming wind for the whole time. Should the wind only blow half the day at that speed, you would still get the recommended full turn over per day.

One thing about the windmills is that for an uninterrupted wind flow they have to be taller than the tallest tree around the windmill.......

Thanks Quarter. My pond is about 330,000 gallons. at it's deepest point, it is about 12-13 feet. From what you're saying, it sounds like this should work for me. I'm also in a pretty windy area

I am in a VERY windy area. 40mph winds two days ago. 25 mph winds yesterday. I would choose an on demand solar aeration unit over my windmills everyday of the week if I could do it over. What Scott said about uninterrupted flow is spot on.