Pond Boss Forums AERATION Systems questions Koenders Windmill problems.

Since a few of y'all have one of these windmills I would appreciate some advisement. After reading the Pond Boss special issue on aeration, and several posts on this website and others with glowing reviews of their Koenders Windmill, I decided to purchase their 20Th Year Anniversary Dual Diaphragm Windmill.

So far my problems have been numerous. I've had to run to the hardware store several times due to missing nuts and bolts and threaded hose barbs. I've also had to deal with bolt holes that don't line up to the point that on several occasions one singe bolt and nut took 20 minutes of prying and pulling between me and my wife.

Now I've got the majority of the thing assembled despite these problems and I'm having a pickle of a time with the spider brackets that go on the compressor crankshaft. The manual says there should be no gap between the spider brackets around the shaft. I've been tightening these bolts evenly a little at a time like it says and I've reached a point that I'm struggling to tighten them anymore and I've still got a gap between the brackets where the manual says there should be no gaps. I'm afraid if I tighten the bolts further I'll break or strip the bolts. I'm pretty sure I'm beyond the 8 foot pounds of torque called for but I'm trying to get to the point of no gap that the manual says you need emphasized to the point that the sky may fall if you don't do this right.

I've tried calling the company but they're closed till Jan. 5th and of course here I am only having time to work on the thing because of having this holiday off work. If it would help on page 20 of the PDF found here is a picture of what is expected, it's for a different Koenders Windmill but seems the same on this part.
Here's the pic in the manual
This is how mine looks so far and here is the rest of it Any guidance on this issue would be much appreciated.

I have no experience with windmills but the gap in your pic should not be a concern. It's tight around the shaft where there should be no gap. The elimination of the gap you speak of will not provide more support. So IMO you're good to go.

Bravada, you have me curious so I dug out the instruction manual on my 20 ft single head Koender.It shows and states a space of 1/8 inch at the bottom of the small "V" coming off of that shaft(large V at shaft and narrows down to this 1/8 inch before spreading out is desired. I dont think youll get it all out and "tight is tight" I would however add lock tite or double nuts to all of those bolts as the flat washers are soft and at some point may let the nuts back off. The top section (12 o clock position) looks like a bigger gap than the other two so might be able to draw those up a tad moreWhen I purchased my mill years ago I let the local dealer put it together and install (way too busy in those days) and I see he has lock washers and lock nuts on this one. I hope you have a better anchor system than just the factory leg stakes as they tend to work out of the ground over time.I think the missing bolts and difficulty getting everything to line up is standard.Yours is the first dual head I have seen as I know Koender talked about it for years. I like the painted look.I replace the check valves and diaphram on mine about every 5 years and other than that it keeps on pump'n.This one used as a winter aerator Good Luck PS I picked up my rebuild kit from Bill Cody and he had a great idea about soaking the pan cake diaphram in WD 40 for a week or so to get even longer life out of them,

bravada, It appears to me that you have the spiders aligned properly and tight enough. Note the small pic you included does not include a shaft in the central part of the spider. A shaft will cause the central spacing (diameter) to be slightly greater similar to your large photo. Plus I think the double headed mill might have a slightly larger diameter shaft than the single head model.


Take Ted's advice and use double nuts on the spider bolts. I went to the expense and bought lock nuts for my entire windmill assembly. For those K. mills that I sold I highly recommended the use of lock nuts - regular or reversable style. Several of the Koender methods of design, construction and assembly have design flaws in my opinion. The way the fan is attached to the shaft with just spiders is one of them. Fan heads have been known to come off the shaft - rarely, but it has occurred. Beckermills Inc in Ohio redesigned and improved most of the problems of the Koender's windmill including getting more air cfm production.

From your photo it appears Koenders also have now skimped on design of the shaft and it is no longer solid steel, but a composite of some sort. Older mills had solid steel shafts. FYI many of the holes between parts for assembly do not align because this is their way of not having to use lock nuts. Their philosophy is if the parts have to be torqued into position for bolting the tension will tend to lock the bolts and nuts into place. When I assembled mine, I used a center punch in both holes and pulled the parts into alignment so the bolts would fit into the two holes. I never liked that idea and it appears they are still using that philosophy.

I big thank you to everyone who responded. I went ahead and added a nylon lock nut as suggested on top of the existing nuts after I tightened it up a little more, just till I thought it might break the bolt. On your PM Ted I've been using a socket and ratchet from the beginning along with some air tools so no worries about a hand wrench making it seem tight.


As far as an anchor system is concerned I used a guy wire attached to a 40" augured tip eye anchor on each leg on top of the supplied ground stakes.



If anyone thinks I should beef it up beyond that let me know not to mention how you would beef it up. I thought about sonotubing some concrete piers but didn't want the aggravation of not getting it lined up right, which is what I know would happen to me given how difficult this has been to put together. Again thanks a bunch, now to get them air stones in and try and do something about the previous owners mess with them cat tails.

Looks good, If those guy wires ever get in your way try putting one anchor dead cener between the 3 legs and then attach the 3 cables in the 2nd or 3rd horizontal cross section(s)That puts all of your cables on the inside of the structure. Use a turn buckle on each cable as you will adjust as times goes and things stretch and settle.On the cats have you looked into Habitat from BASF,

Nice work Bravada and your place looks beautiful. I like how your house is oriented to the pond. Looks like is has a great view over the pond.

So tell us a little about your pond. What kind of fish are in it? How big is the pond? What are your goals for the pond?

I did read a bit about the Habitat herbicide and Clearcast Herbicide. I'm not sure where I can buy it around me and the one place online I found that had prices wanted $750 for 2.5 gallons. I understand that it's concentrate but that's still pretty expensive. I guess the big thing is finding it locally. At some point I'll do a little searching on this forum for more information.


The pond was put in by the previous owner. The pond is elevated from the surrounding land. I'm not sure why he did it that way but it's my understanding it's a good thing as far as keeping bad runoff out, and nature from filling it back in so fast. It's about .6 to.7 acres guessing since it's roughly 275' X 100'.

The pond was stocked by the previous owner and I can't recall everything he said was in it, four or five different species. The only thing I've caught is large mouth bass, but after a fish kill, which is what prompted the windmill, I found several 30" catfish and 19" bass. In total I found over 30 fish of varying sizes dead at the banks and in the water.


To be honest with you I don't have much fishing experience and therefore have a hard time identifying the different species. Ideally I'd have more time for fishing and when I do I'll get to learning what's in there and how to catch it. I've been a city dweller all my life so living in the country is new to me.

My goals for the pond is for it to look like this all the time. This is the view from the back of the house.

And to keep these guys happy. Black bellied whistlers guessing from my bird book.

My hope with the windmill is a healthier pond for the fish to hopefully mitigate further fish kills. It would be nice if it helps with the vegetation but I could see pumping oxygen into the water makeing that worse but I'll deal with it as needed.

Great aerial photo. I like how you have a pennisula in the middle of the pond. The rest of the photos are fantastic as well. I love the rainbow photo. That is magazine worthy, consider emailing it to Bob Lusk for the magazine. I'm not kidding.



Wow that's deja vu all over again. That is exactly what happened to me. When I bought my pond property I was told it had LMB and BG in it. Turned out it was LMB and GSF and no BG. I was also told the pond was 40 feet deep right in front of the dam. Turned out it was 17.5 feet deep in front of the dam. The people that had previously owned my pond basically knew nothing about it.




LOL, ok I think were're brothers from another mother. When I bought my place I had not freshwater fished in well over 20 years. I had done some salt water fishing (a once a year trip for several years) but no freshwater fishing. I had know idea what kind of tackle to buy or how to fish. I went to Wally World and bought what looked like a reasonable looking pole and some miscellaneous lures. My wife (aka JWHAP) bought this goofy looking pink bug thing. I commented "a pink bug, honey that will never catch anything." Turned out to be one of the most productive lures that we have. Like you I found this site and started posting. The people here are great and have real patience with us amatures. If you can find a friend nearby to your pond that fishes they can help you a lot with tackle and technique. I found DIED on this site and he has been an enormous help to me and has turned out to be an incredibly good friend.




Any pond questions that you have always post them here. The folks here are great and we have access to the best minds in the pond business. Also some of the most dimented minds in the pond business but I won't mention any names.