Pond Boss Forums AERATION Systems questions Windmill or Electric?

Rookie here...please be easy on me. Up until 3 years ago I had a gravel pit on my property and had the landscaping company give me a pond when finished. Right now the pond is about 1.5 acres and maybe 8-10' deep. If and when the pond ever gets enough water to fill up, it will be 2.2 acres and about 12' deep. I have not stocked anything in the pond yet but want to this year and have been told I need aeration. I have a nice hill above the pond to put a windmill on and if I had to, I could run power to the pond for an electric system. I would like some advice on which way to go. Like everyone else, I want the cheapest upfront and operating cost. I really don't want to trench in a long AC run so I am leaning towards a windmill. Here is some more info and pictures of my pond:

http://goldenpondfarm.com/minnesota-fishing-farm-pond.htm

I would like to get the aeration started and I would like to stock the pond. It was suggested I could add some Blue Gills, some Large Mouths, and maybe even a pair of Pikes.

Thoughts, suggestions, idea?

Thanks!

Lew

A windmill would have the lowest operating cost - energy is free and you have small annual (or less frequent) maintenance costs. The last time I compared setup costs, they were roughly a wash (maybe $200-$300 difference depending on whether you were comparing deluxe apples to average oranges or vice versa). The aeration Pros can give much more exact quotes on prices as well specs such as air delivery, etc.

I have a windmill. I like the no-electric-bill part and I enjoy having the windmill spin around at the pond instead of hearing compressor noises.

BUT (and it's a big but), you can do a whole lot more with electric aeration than you can with a windmill. You're not dependant on the wind blowing, which might not happen when you're under a fish-kill threat in mid-Summer after a dense algae bloom dies and you really need the extra oxygen in the water. You don't need to pay for electric to run it 24/7, because you won't need it all the time (some months probably not at all). I think most compressors are capable of driving more than one airstone/diffuser, and most (or all) windmils aren't. And you don't have to bury a long electric line to take power to the pond, you can put the compressor (and the noise) at the nearest electric source and bury the airline - some of us consider that safer than and/or preferrable to buried electric.

I think if you are planning to intensely push to envelope in your pond (fertilizing, heavy feeding, highest possible weight of fish) you are much better off with the capabilities and capacity of electric aeration. If you plan a more laissez-faire approach, a windmill will probably prove sufficient.

Right now, I am happy and believe I am well-served by my windmill. But if/when I retire, put in a second pond, and push the envelope, I should probably put an electric compressor in my nearest barn and run airlines to both ponds. The windmil will probably need replaced by then anyway.

I think Theo covered it all. Very good advise.

Thanks for the conformation that a windmill system is most economical. I assumed but didn't know if there was a big difference of system costs such that you would need to get free air for awhile to offset higher initial costs? I already have a pool pump running 24/7 which is enough noise for me...

From my house to where the aerator would be is about 400-500'. If I put a windmill on top of the hill, it is about 100' from the compressor to the aerator. Of that 60' would be trenched, 20' on the tower, and 20' in the water. If I ran a line from the house it would be 400' of trenching. Won't I get a huge flow loss running 450' vs. 100' requiring a bigger pump running more HP and costing more?

When I initially considered aeration was to avoid winter kill because my pond isn't deep/big enough. I was told you needed 14' here to avoid winter kill. When I decided I wanted fish I knew I would have to aerate. I have no intent to use the pond commercially. I just want fish in the pond... Having just decided to have fish in the pond, I had to then take the next step which is why I am here. Aside from getting a windmill or whatever for aeration, what else do I need to know or do? I am already working with the county on some emergent species and I planted some seed last year of wetland grasses and forbs but nothing came up last year so I am waiting to see if I get anything this year. I am still intending to put some plant species in the pond. The wild stuff that has moved in is mainly cattails and willows. I was told to kill the cattails to give the other things I am trying to grow a better chance.

goldenpond, if you are going to add warm water species (ie largemouth, bluegill) you may want to read some of the posts about supercooling a pond by aeration in the winter. For 2 years I couldn't figure out why my fish were coming out of winter in such poor condition. This winter, I did not aerate and avoided winter kill through other methods, my fish are in spectacular shape this spring. I believe it made a HUGE difference in the body condition of my bluegill.

Thanks for pointing out the info on supercooling. I hadn't heard of that... I only found one topic containing the word supercooling. Sound like the suggest was to aerate at a shallower depth. My pond isn't deep, it is only about 8-10' deep...maybe this information doesn't apply? Are the "problems" with deeper ponds? Maybe I am not getting it?

Lew

I don't remember ever seeing a post that was really enthusiastic about the results of windmills. I could be wrong but I think more people are happy with electric when they learn to use it properly.

When checking the link on supercooling one of the guys providing feedback had three windmills on a larger pond. Maybe he had no choice on the use of windmills.

I don't doubt there is an advantage to having air when you want it and how much you want. I really don't want to put in a 450' trench to run tubing however.

The first two replies to this thread seemed to confirm that a windmill would be best for my application.

Even if a windmill is not the ideal situation, will it be suitable or not? Seems like there is a whole lot of these windmills around and I assume some are being used when electricity was a choice?

It seems I need aeration, it is just a question of whether or not the windmill will provide enough air or not. This is Minnesota afterall, the coldest place in the lower 48...

Thanks,

Lew

There are some good threads on supercooling with Dave, Bruce, Bill, etc. I think in your case, moving the airstone to a 3-4 ft. may do the trick. My pond leaks slightly, so I just run some water in my pond to keep the surface open. There are several more threads that have supercooling in them, if I get time I will dig them up.

When I did a search on supercooling I only got two hits...this message string and another with a lot of results... you are obviously giving up a lot of water movement by raising the stone up...I guess that is the point of the theory, right?

Lew

You should be able to prevent supercooling by putting the diffuser/airstone in shallow water or shutting off the airflow. With a Windmill, put a "T" in the line and just let it bleed off freely.

The plus side of a 450' ditch is you won't dig it by hand. The 60 footer, you might be crazy enough to do it yourself with an idiot stick (I was!).

Since there was only the one string that I could find on supercooling, is it still in the hypothesis stage or is it "real"?

I am even more confused if you are suggesting bleeding off the air when in fact getting air in the pond and keeping some surface water open was supposed to be the concept of having aeration, wasn't it?

Initially I was told I needed aeration to get the fish through the winter to avoid winterkill and now you are suggesting I not use the aeration in the winter?

Deeper ponds and lakes have managed for eons with no artificial means and I thought aeration was applied to a pond that is too shallow to survive on it's own?

I know there are people on here who use their ponds commercially and want things perfect for maximum fish production. I would like to have fish simply to have them and would just like them to survive and have what oxygen they need and the removal of obnoxious gasses that I thought the circulation also helped with?

Lew

Let me try to clarify as perhaps I have muddied the waters.

About Winterkill - you need to worry about this when you have a solid ice cover AND sunlight cannot reach the water - typically from snow cover but I supposed that really milky ice could also be a culprit. Cold water holds more oxygen and fish need less oxygen when cold, so if sunlight can get into a small part (1/3? 1/10? I think I have seen figures in that range) of the pond there should be enough O2 for the fish. If there is snow over ice, you can let the sunlight in by 1) aerating a hole in the ice or 2) snow removal over part of the pond. I believe guys like Wood way up North (Sometimes I think the only direction Wood can go is South) have to use snow removal - he gets multiple feet of ice.

About Supercooling - Water is the densest when it is 39 deg F (4 deg C), so in an undisturbed frozen pond, the water on the bottom will typically be 39 deg. The water just under the ice would be 32 deg. You get supercooling if you aerate a hole in the ice when the air temp is below freezing - this draws residual heat out of the pond and can lower the water temp from what it would be otherwise. Your bottom water can get colder than 39 deg F, which can stress fish that don't like cold water.

Is Supercooling real - yes, it can happen (or perhaps it would be better to say it does happen to some extent, possibly noticeable) if you aerate when the air temp is below freezing.

Is Supercooling a problem - depends on your situation. If you are trying to have Redears in Nebraska, a situation where Winter survival is on the hairy edge, I would say you have to worry about it. If you are raising cool/cold water fish (SMB, YPerch, Walleye) in MN, probably not a concern. BG and LMB in MN - perhaps you should watch out.

Aeration in Winter is not needed as often as in the heat of Summer. If you are watching out for Supercooling, you would want to limit your aeration time and do it when the air is relatively warmer. The Pros (as I remember) think that it is better to let the pond stay frozen over for up to a week than to over-aerate (and supercool) if the air is really cold. Unless you have an old pond with a heavy, decaying organic sediment load, noxious gases should not be a problem in this situation.

If I have confused you further I am sorry, and I guess we'll have to restart the Supercooling thread to get real experts involved. Whether you go with windmill or electric, supercooling can be avoided if you need to. I am sure the topic will be discussed more next Winter.

-Theo

Theo-

Very good examples and descriptions!

goldenpond- Because the colder water in winter retains more oxygen and the entire aquatic habitat is slowed to a hibernation pace, not as much aeration is required as is needed during summer.

The aeration system name is not named correctly. It should be called a de-icing system during winter and a circulating system during spring, summer and fall. The transfer of oxygen is less than 5% in the bubble. The actual aeration effect takes place at the surface where the "bad" water that contains Hydrogen Sulfide and Carbon Dioxide gases is released and since this water is low in oxygen it pulls in oxygen molecules and eventually circulates this oxygen rich water back down to the bottom.

By gentally moving the water at the surface during the winter, the ice is unable to build. This allows the sun to penetrate and allows hydrogen suflide and carbon dioxide to escape.

The problem with your long trench is the fact that either by a Windmill or by an electric compressor, you will be compressing atmospheric air that will contain water. That water will build up in the dips of the feeder tubing and if this tubing is not burried below the freeze line, these areas will freeze and plug the line.

You need to make sure you have one of the following so you do not have an ice build up in the line to the lake:
1) a positive slope down hill with no dips
2) the line burried below your freeze zone
3) insulate the line with a hot water insulation.

The windmill company has an option of an injection of a chemical to deice the line if it does become blocked as well.

I have used rubbing alcohol to remove plugged lines in the past. Since it is such a small amount, it was immediately diluted once it entered the water.

I even had one Aquaculture Customer in the mid 90's who did not heave my waring about line freezes and his entire brood stock pond froze over. He whent to extremes and poured blue dye on the snow and ice so the dye would retain the heat from the sun and help to melt the ice. He also used the alcohol idea and it worked.

Cary -- good idea!! Let's start calling them de-icing systems! That should cut down on a lot of the confusion on what we are doing and why!

Others intersted in this string: I interacted with Lew this morning via e-mail. Let me put a summary here. SDSU is located almost straight west of Lew, so we probably have similar winters (his may be a little milder just south of the Twin Cities). The true gravel pits around here (those dug down into the ground water) do not need aerators as long as they have 10-12 feet of water. Apparently, there is enough ground water movement to keep the dissolved oxygen from hitting zero. That was a surprise for me to learn, as "everyone" says that ground water has no oxygen. However, the shallow aquifers must have some.

In contrast, the hill ponds (dams built across draws) around here have to be VERY deep to avoid winterkill. During that last bad winter (2000-2001, I think) we had winterkill on two ponds that had aerators and were quite deep (one is over 20 ft). These ponds were 3 and 7 acres, so it's not like they were tiny. Winters are tough here. However, this is when I first learned about the potential for "super-cooling" of water over a long, hard winter. Several of us from the Pond Boss Forum monitored dissolved oxygen and temperature this winter, and found little evidence of super-cooling. However, it was a very mild winter (ice was not especially thick, and little snow cover on the ice). So, it probably was not a good test year.

Anyway, here was my thought for Lew. If he had time (that is, could wait a year), I wondered if he should monitor dissolved oxygen next winter and see if he really has a problem?? Just a thought.

Thanks for all of the additional information... If I am not mistaken the bottom of my pond does in fact "connect" to ground water, but the ground water level can also raise and lower so even if the hole originally was dug slightly into the ground water table, that doesn't mean it still is. I would assume most ponds are like mine, i.e. they are in a depression. That means the snow will naturally collect on the pond, even more so than whatever falls on the pond. Even when there hasn't been much snow, the pond was covered pretty thoroughly. I am not in a position to clear the snow off of the pond.

I think I got it regarding the supercooling.. It makes sense to me piping in air that is colder than the water would cool the water. What I am concerned about is it can go a long time here when the outside temperature is below freezing and in that time the water will ice back over. Because my pond is fairly shallow I guess I am even more concerned about the freezing and lack of oxygen. I just checked the average winter temperatures here. The average high temperature from December to February is under 30 and the average low is around 10.

Other than occaisional days when it is above 30, it seems like there would be little opportunity to pump "warm" air into the pond. I hadn't heard of the issue of ice crystals jamming up the airline. I didn't know what it was needed for, but the windmill company has a freeze protection option for a nominal cost. I don't know well the work but I hope they do the job. A part of the system is a regulator to help prevent damage if the line becomes blocked.

Thanks David for the private mail which you recapped here.

Lew

Lew -- the supercooling may occur just because of the water circulation. Water is heaviest at 39 F, and that water is on the bottom of a pond during the winter. At the surface, of course, it is 32 F where it freezes. The supercooling thought is that too much circulation brings up too much warm water to the surface where it cools. As a result, bottom water get colder than it should, which may be hard on some fishes.

I'm not 100% how much aeration/circulation it takes for this to occur. Others on this forum know more about aeration systems than me, and they may chime in. However, if it matters to you, we are putting a new windmill aerator in this year on that 17-acre pond that I mentioned to you earlier. To be safe, we plan to put the diffuser in only 6-8 feet of water, rather than in the 26 foot deep water down near the dam. We've got one of those Vertex diffusers from Ted Lea (he helps on this forum), which has very small pores. I'll be interested to see how it performs next winter.

Something else just came to mind... I just talked to the DNR and was reminded just how thick the ice can get. I think he said 3-4 feet is possible. If the pond is only 8' deep and 3' is ice that doesn't leave much distance from the bottom. If I was to suspend the airstone higher up and then not run it all the time to avoid pumping in cold water, then couldn't the ice actually freeze down to the height of the airstone? Seems with a pond only 8' deep that there might not be a choice on what depth to put the airstone at?

Lew

Lew -- as we discussed by e-mail, we get about 14 inches of ice in a mild winter (this past year), and up to 30 inches in a bad winter (2000-2001 was a bad one). Maybe do a little more checking and see what range in ice depth to expect. If really is 3-4 feet, that will be tough!

Goldenpond, I can share what has been working for me, I won't call it advice, as I am still learning also. Air pumped into your pond contains about 20% oxygen. Air produced by plants and planktons is near 100% oxygen I believe. My trout have succesfully wintered two years now with 200 days of ice cover, max ice thickness 37" with seven feet of water below. No aeration, but I removed snow cover within a few days of new snowfall on about 3/4 of the pond. I tried to aerate two winters ago and had problems with airlines freezing. Lower fish densities probably helped with keeping d.o. levels up also. Most ponds around me do not use diffusers in winter, either nothing or top water splashers.

Thought I wrote reply but don't see it???

Anyway, I don't have the equipment or ability to clear the snow from the pond. Heck, my driveway doesn't even get plowed half the time.

I can do nothing or aerate...

Lew