i have a 1/4 acre lined pond in wisconsin. pond is obong, ranging in depth from 3ft on one end to 12ft at the other. pond is 4yrs old, and is stocked with yellow perch, hybrid gills, black crappie, and last spring largemouth.up until last winter i turned my aerators of in mid nov with no problems. last winter i had one aerator running at the shallow end, about five ft from shore. in spring i had about 8 dead largemouth. wondering if i a better off with the aerator on or off for the winter.

Typically you want about 10% or slightly less of the total surface area in open water in 1/4 the total pond depth for the winter. How much of an area did you have with the aerator that was running?

1/4 acre is roughly 10,000 sq. ft, so you should have around 500-1,000 sq. ft. of open water. That's a circle 26' to 40' across of open water......

Largemouth do not tolerate super chilled water below 39F as well as some of the other fish you have in your pond. LMB are prolific and the pond can tolerate some loss of a few LMB compared to a heavy winter fish kill without winter aeration.

esshup, i probably had a larger area open than 26/40 inches. should i keep the aerator that close to shore, and close the air valve to obtain the 26/40 inch opening?

Jeff,

I think Esshup means 26 to 40 feet.

DA!! SILLY ME.

I'd like more information on this as well. My pond is about 3/4 acre with two 10 foot deep pools. Like the OP I have bluegill and bass in my pond. This is the first winter I've not ran my aerator this winter at the suggestion of NEDOC and for the past 2 weeks its been frozen over. It makes me very nervous! NEDOC suggest that running the aerator when it is cold outside will chill the water too much and be hard on the fish. His logic makes perfect sense.....but I'm still nervous!

Guys will tell you out here that iced over ponds are not the real problem it's snow covered ponds that are! As long as the sun can hit your pond it will produce some Oxygen in it. That's when this becomes a real problem. Lots a guys I know in the north make sure they keep part of their pond cleaned off the best they can from snow for this reason.

RC

P.S. My Grand Father had a pond in Rudolf Wis. As a kid I always remember him running a surface air station in winter. Not sure but maybe a surface air setup would not effect the water as much as far as super cooling it? Plus it kept a 15 to 20 foot surface area cleaned off pretty well.

It's usually recommended to aerate shallow during the cold months, to avoid the supercooling effect. What you are shooting for during winter aeration, is to clear an area of snow/ice, NOT turn over the entire water column. If you have clear ice with no snow cover, you may be fine without aeration. I won't chance it, and will crank up the diffusers whenever I get extended intervals of snow cover.

Haven't needed to do that thus far this winter....

Ma Nature threw me a curve and I haven't decided how to proceed yet. In the fall, my pond was around 10 feet deep and I set me winter diffuser in 3 feet of water, about 30% of pond depth. Good to go, right? Along comes the curve ball in the form of heavy fall rain and the pond coming up 4 to 5 feet. My winter diffuser is now in 7 to 8 feet of water in a 14 to 15 deep pond, 50%+. I can't move it so I think I will limit aeration by running the diffuser only long enough to blow a nice hole when snow covered (I can turn the compressor on and off from the house).

I do the same thing, running two aerators (of 4) to open up the water, to clear off the snow, then shut them down again.

I did this before they called for 6-10" of snow yesterday, we ended up getting 1". I shut them down this morning and have 2 nice 50'+ areas now opened up to freeze without snow cover.

I don't ice fish or ice skate the pond so I don't have the concerns of thin ice.

Ice is rarely the problem. The problem is snow on top of ice for longer than 4-6 weeks. It takes several weeks of snow cover for the DO to begin a decline toward a concentration that will stress fish. The clarity of water at freeze up also plays a big part on how long DO will last in dark conditions. Remember as the water first freezes in winter, the DO top to bottom is always at maximum concentrations (12-14ppm) with full saturation at 100%.

In relatively clear water and most everything in a dormant phase at freeze up, it usually takes several weeks (cloudy water) to a couple months (clear water) of compete darkness before the water near the bottom to loose its DO to where fish are forced into shallower water where DO is higher and above 1-2ppm. The deeper the pond the longer the DO will remain high enough in the upper layer for fish survival. DO is lost from the bottom upward. Fish in winter in water 39F are able to survive in a lot lower DO compared to low DO in summer temperatures when the fish's metabolism is higher and requiring significantly more DO for respiration.

That's exactly what I was trying to say!! Nice Bill C. as usual nice!!

RC

I thought the hole open in the ice was also important for the gases to vent? Is that not a significant factor?

Generally there are few if any gasses (toxic) that need to be vented until significant amounts of anoxic conditions develop to produce the gasses. Anoxic often is at a minimum until the extended snow covered ice develops. It is my understanding that the primary "gasses" that need to be vented are methane and hydrogen sulfide, both not produced until anoxic conditions (anaerobic) develop and after the DO is exhausted.

So, not to beat a dead horse but are you guys saying you wouldn't run aeration (in shallow / 10% of the pond) ALL of the time but simply turn it on when the pond has had snow on it for a week or two blocking sunlight? And even then, only run it until it pops a hole through and then shut it down until it happens again?

I normally run 3 diffusers in the summer and running one now but I had too much pressure from running just a single diffuser so I stuck a hose into the edge and let it bleed off the pressure (stuck it under a pile of pallets to keep it there). That "bubbler" alone opens 10-15 feet diameter and I don't think it "circulates" near the water that the diffuser does - maybe just run that open line without the diffuser?

Northern ponds especially those that have 3"+ snow cover should be aerated in winter. Need for aeration increases after complete snow cover has laid on the ice for 2-3+ weeks. The deeper the northern pond the less need for winter aeration. Deep water results in high volumes of water with lots of DO at ice formation. The more the percentage of the pond with deep water 15ft+ the less the need for aeration in winter.

Another factor is how much snow is removed by wind to create clear or snow free ice. Snow free areas of 20%+ results in less need to aerate. Sunlight that penetrates ice cover causes phytoplankton in the water column to produce DO 2 times deeper than the light penetrates into the water. Example: if water is clear (vis 5ft) and no snow is on the clear ice phytoplankton will produce dissolved oxygen in water up to 10-12ft deep.

In some northern ponds (7-12ft) with less snow or shorter periods (2-3wks) of snow cover, aeration is not usually necessary unless the pond contains lots of dead organic matter, thick mucky bottom sediments and/or old growth submerged vegetation which all consume significant amounts of DO during the winter ice cover period. Winter aeration becomes an important factor for fish survival in these ponds.

All the above factors determine how much aeration is needed and how often and how long one needs to operate winter aeration. My pond at 14 ft deep currently has 2" of ice with 1" of snow. I have not turned on winter aeration as of Jan 16. I will start aeration when 3"-4" of snow has accumulated for 2 weeks. I will aerate until I produce a large ice free area 20ft-50ft dia; then shut it down. Open water allow lots of sunlight to create DO in areas surrounding the open water. Then aerate each day until I recreate an ice free area 40-50ft dia. Cold winter water circulates very easily so any DO in the ice free area gets widely distributed to far areas of the pond. To date I have not been able to measure how far the aeration currents spread the cold water & DO beyond 150ft.

Thank you Bill - I will go turn mine off then. I started it once the ice was on. We have maybe two inches of ice and less than an inch of snow on it. The weather has been unseasonably warm lately. The water depth is 14 ft in the deepest.

Also, the thicker the ice and the more opaque it is, the less sunlight will penetrate the ice. In other words, if there's 12"-18" of ice that is very milky in color, I would err on the side of caution and fire up the compressor and open up the pond. I'd actually probably fire it up sooner than that, but just using that as an example. A couple dollars of electricity vs. the dollar amount of fish in the pond is a cheap insurance policy in my mind.

I pretty much do it the way Esshup describes. The only thing I will add is I try to blow the hole on a "warmer" day if possible. My thinking is when temps are really cold, that snow/ice cover is acting as insulation and keeping the water a little warmer maybe. If there is going to be a warm up in the next few days, I wait till then to blow the hole. Also, the air you are pumping into the pond is warmer on a warmer day so not chilling the water as much as pumping super cold air.

Just my 2 cents

Bill D., take a thermometer and check the water temp. A few years ago I thought that air going into the pond would change the temp. Like aerating at night only when the night time temps were below 70 to help keep trout alive.

On the contrary, I found that the water actually warmed up faster because of the upper and lower water temps mixing and the trout croaked faster than if I were not to aerate at all.

I even purchased a special thermostat that would turn on the aerator when temp fell below 70, and turn it off when temps climbed above 70.

Air being injected into the pond via an aeration system, by itself, does not change the water temp enough that you can measure it. It will change the water temp by making more of the water volume contact the ambient air, but in the winter, warmer water sinks. So if you have the diffuser placed in shallow water like is recommended, you will not disturb the deeper, warmer water.

Interesting discussion. Right or wrong, here's my thoughts...I agree the pond definitely warms faster when aerated during the summer. I do still think, that if you have to aerate in the summer, the pond will warm less aerating in the cool of night than aerating in the middle of the day. Simple heat transfer principal. Heat moves from hot to cold. The rate the heat transfers is proportional to the difference in the temperature between the two points.

Same with aerating in the winter. I think you are better off aerating on a warmer day. Although the water may not move from the deep part of the pond, the heat will transfer to the adjacent water if the temperature in the adjacent water drops. The more the temp drops in the adjacent water, the more heat that will be transferred from the deep water. I also believe the deep water temp will slowly recover as it pulls heat from the pond bottom. With all that said, I doubt the temp differences are huge but I figure every little bit helps!

I think heat transfer is continuously occurring in a pond whether it be from the pond bottom up during winter or from the surface down during summer.
Transfer will always be occurring as long as a temperature differential exists to drive it.

That is true. Will the difference in temperature be enough offset the gains/losses in the different O2 levels?

Lets take summer aeration.

A pond owner is wanting to keep trout alive for a longer length of time into the summer months, so they want to keep the water temp below 70 degrees, to help keep the DO high enough to keep the trout alive. Will aerating at night when ambient temps are below 70 be enough of a difference between aerating during the day when ambient temps are 80 to keep trout alive longer, or will not aerating at all work better, i.e. allow the trout to live longer?

In the winter, if a pond is aerated on a 10°F day vs. a 25°F day, for the same amount of time, what will the temp difference of the water be?

I agree. That's why I prefaced my statement with "if you have to aerate in the summer" then do it at night. For your trout scenario then I would not aerate at all. You are warming the cool bottom water by mixing it with the 80 degree surface water. The cooling by aerating at night would not be enough to compensate for that. Let's ask the question another way, do you think a pond aerated in the middle of hot days will rise in temperature faster over time than one aerated during cool nights or no difference or hot day aeration will result in cooler water?

For winter I was thinking more a 0 degree day with howling winds vs a nice sunny 35 degree day but even in your scenario I would think there will have to be a difference, the greater the temperature difference between the water and the air (wind is also a factor), the more heat that will be lost. Is there a huge benefit, I doubt it but as stated above, I figure every little bit helps.

This is just a thought and may be wrong. But I was thinking that at times of the year some fish hug the thermocline level.

Could it be that by not disturbing the thermocline, keeping the lower water cooler for the trout, they could hug the thermocline and dip in and out of the cooler but low DO water and into the warmer but higher DO water? Don't know, just asking. The thermocline is generally a vary narrow band where the change takes place. Maybe they would hang out in the transition area.

Bill D one other thing to remember, the aeration does not turn the pond into one big homogeneous mass. At least not in my pond. Maybe if a person had excessive water movement it would.

In my pond on a hot summer day, I can swim towards an air station and about ten foot away feel a distinctively flow of cool water at the surface. The top is heating faster than the water flow from the bottom is mixing.

Who knows, maybe I don't have sufficient flow for my size pond. But I would think at the desired one turn over of water volume per day (or more) water temperatures within the pond are still going to vary.

On the other hand, in my 1/20th acre forage pond and 1/10th acre sediment pond, I may have enough air flow to keep them homogenized. But not in my 3 ace pond.

So mixing at night or mixing in the day only may not get the results imagined, unless a person has a fairly high flow rate of water to turn the pond over fairly quickly. Takes time to heat or cool or mix millions of gallons of water.

Just the way I see it. Don't know if it is right.

100% agree. I am not saying there is a huge difference, just saying there has to be one...unless the second law of thermodynamics is wrong.

I have wondered about that. Is it lack of DO that kills the trout or the temperature or both? If you could somehow raise the DO level in 80 degree water, would they survive?

It's a problem of both. Trout need a minimum of 5.0 ppm O2. Take a look at a DO chart and see where that falls.

A client that has both surface agitation and bottom diffusers has had Golden Rainbows living in 78 - 79 degree water, but they did not make it through the summer. O2 was at saturation levels when I checked it.

Several months ago I remember reading a post by one of the aeration experts where they gave an approximate time for a winter diffuser to cut thru X inches of ice. Anybody remember the numbers? Just curious, I know I have a thick ice cover here. Got some snow on it and fired up the winter diffuser at 7:30 this morning. Still no sign of breaking thru 5+ hours later. A lot of air (4 to 5 cfm) coming thru that diffuser. I walked down and checked, thinking I might have a frozen line but system pressure is normal and all appears operating as usual.

Has to be one big bubble under there!

Bill, to speed up the process I will go out and drill several 3/4" holes (largest long-bit I have/had) over the diffuser area. It breaks through much quicker! Of course an ice-fishing auger would be preferred, I just don't have one.

But a forewarning: I had my system running which had built up pressure, likely what you have now in your pond, and when the drill broke through the ice,,, well,,,, old faithful went a spewing upwards!

Kinda cool actually, but don't say you weren't forewarned

Oh, and be sure your bit is tight in the drill! Mine apparently wasn't and it slipped right down the hole to the bottom of the pond. So now I'm using my last long-bit which is 5/8"

I can see how that would help but there ain't no way I am going out on the ice now! Still no hole after 7+ hours. I am wondering, as the ice cover has been on there for quite a while, if the water table dropped some and there is a gap between the bottom of the ice and the water level. Anybody ever seen that?

Never mind.....There she blows! Mission accomplished 7 hours 32 minutes to break thru and it is off to one side of the diffuser so must have found a thinner spot.

Bill, I've always understood there to be an air gap between the ice and the water, but maybe I've been watching too much TV

In the past, with all the air being pushed against the ice, I've seen it escape at the shoreline but also wondered how much pressure it's creating, if it is, such as yours running for 7 hours before breaking through! I do know there has to be a tremendous amount after witnessing Old Faithful on my own pond.

Does all that pressure have any adverse effect on the fish (stress to a harmful degree)?

Keith,

I've always heard the same thing about the air gap. The movies where people fell thru the ice and get air in the gap. If there is a gap, how can ice keep getting thicker when it's not touching the water? The ice fishing guys should know if they see a gap when they cut their holes.

This is the first time I've seen my winter diffuser blow a hole that's not directly over the diffuser location. This one is starting just a few feet from shore, about 20 feet from the diffuser. Maybe its water depth? Although the diffuser is in the same spot as last year, the November rains brought the pond level up. The diffuser is in 7 or 8 feet of water this winter instead of 3 or 4 like last year. It's weird!

IMO I don't think you can build up pressure in the pond very "high." Your compressor has limits on the pressure it can output.

If the water level drops after ice forms there will be an air space directly under the ice. This is an indication that your pond likely has some sort of seepage - leak.

Yep, it's a water table pond.

I've had ice cover for two weeks with some on and off thin snow layer. Today there was 3.5" of ice and 2" of snow cover. At 13 ft deep water at one ft deep DO was 11.8ppm, 39.2F with 90% DO saturation whereas at 2" from the bottom DO was 11.4ppm, 39.6F with 85% saturation. I will not start aeration until the DO on the bottom is 2ppm.

Yea, about 150 psi. You really don't want to be standing around it when it blows.

Wow! The relief valve on my aerator compressor is set at 35. Why do you have yours set so high?

Typically in a pond where the water level drops, the ice along shore will slope down to the water, then the ice floats on top of the water. Ice will have a hard time staying horizontal if the water level drops as it is only frozen to dirt.

Just like you trying to hold a sledgehammer at arms length, the further away from the anchor point (your shoulder) the harder it is to hold up. Ice does the same thing.

Somewhere on youtube is a video of ice in a pond breaking from air forced in from an aerator. The ice looks like a balloon.

For me in my location, with only running during the day time hours, bitter cold freezes up the ice over the aerators every night. It takes a while to open a hole sometimes weeks if I don't go and drill holes over the diffuses (which I hate doing!)

This season we placed some logs floating over the diffusers. They draw the heat during the day, provide a lot of surface area and allow a hole to open quicker the next day. I will be replacing them with "man made" ABS logs this weekend. I think beavers in the north have the right idea for keeping water open

This has got to be the problem at my place. We must have just not had enough consecutive hours of wind to punch through.

I figured that air would move horizontally along the ice and escape at the shoreline or something. Are you guys saying that it will actually stay trapped under there and lift the ice?

Is there any benefit to the aeration if it cannot get a hole open in the ice?

wbuffetjr I think you may be right about not having enough hours of wind at any one time for your circulating pond water to cut a hole up thru the ice. mnfish may be on to something that you could incorporate next season. Even better for you with all your snow cover might be to drive some vertical pipe, posts, or the like, into the pond bottom near your diffuser. The vertical pipe would absorb heat from the sun and tend to have thinner ice right by it.
Your circulating pond water would have to do less work to break thru the ice when the wind did return. Just a thought.

When first starting my aerators in winter I always drill a few holes above the diffuser. Air that breaks the surface seems to cause more splashing action that seems to melt ice faster. NO proof just guessing and watching air-water splash up through the ice holes.

WBJR,

IMO another factor to consider is amount of air, CFM. If you are running low airflow, I would expect longer break thru times. I don't know your setup CFM capability or number of diffusers. IMO Since you can't run 24/7, I would push all the air you can generate thru a single diffuser to maximize your ability to create at least one hole in the shortest amount of time.

FWIW it took me 7.5 hours to blow a hole thru probably 4 or 5 inches of ice at 4+ CFM thru one diffuser station. I suspect I could probably open a hole with 1 CFM but it would take a really really long time running continuously. I would be surprised if I could break thru at all running 1 CFM only 8 hours a day or so.

I fired up 2 of my 4 diffusers (the shallow ones) late Friday afternoon to get some open water due to a few weeks of snow cover and they still haven't blown through as of this morning (nearly 3 full days).

What's happened though is that it's opened up 2 small areas near the shoreline of the deep area, about 100-150' from each diffuser, where the air is now escaping.

I normally do as Bill Cody suggests, drilling holes above the diffuser but I got impatient on Friday and it was getting dark, so I just started them up.

Now I have all these things running through my mind of what's being stirred up with no place to go other than being trapped below the ice until it escapes near the shoreline. And of course it's now not safe to get on the ice to drill holes.

I'm tempted to shut them down, let it refreeze and go back out to drill holes. I know Bill Cody says he has no proof of how drilling the holes help, but taking the least path of resistance, I can't see where it wouldn't and it's always worked for me.

Worked so well I decided not to do it, I guess

PS - the gauge on my compressor reads 5 cfm with both fully open. If I close one, it will be at over 10 unless I pull a hose to release pressure.

4Corners - I am definitely all ears and appreciate any suggestions. I think you are right. I need to come up with something this summer to put out there. I would just want to be able to put whatever it was in when I leave in September and pull it out when I come back in the summer. Just wouldn't necessarily want to look at something out there all the time.

Bill D - this is straight from Koenders...
"The compressor is capable of pumping 28 lbs pressure, but will only pump the amount necessary to push air into whatever depth water you have...for example 10 ft of water depth will require about 4 lbs. (aprx .4 lbs per ft of depth) And it will only require about a 9 mph wind to do it!
It will pump useable pressure as well as volume. The volume again varies with water depth. At 1 ft of depth you will get 3 cfm...at 10' about 2.5 etc."

I have 2 vertex diffusers out. One at 6' and one at 10'. Pond is 22' at deepest.

As far as wind speed up there..... My buddy spent the weekend up there at his place (350' lower elevation than me). Last night they had a big storm blow in and got 20" of snow. He keeps a windmeter out that he said recorded an average windspeed of 20mph! I KNOW we get a TON of wind up there when I am there. I expected this windmill to be more effective than it appears to be.

Having the object in the water is definitely an interesting idea. Check out this picture. The snow around the little generator shed and the big rock have clearly been melted. I can only guess that was from the sun heating them up. The sun up there is definitely "different". You could probably fry an egg on the hood of your truck when it is 70 degrees outside. Maybe the metal pipe trick would work.

Wow that"s some serious snow depth! Good thing your ponds and lakes up there are probably oligotrophic!

If you want to remove it in summer then I would take a 2 or 3 inch pipe however long you need and weld like a 12x12 inch platform on it or 15x15 so you could just set it near your fusers. Make like 3 or 4 or them and put them all around it. Course this would only work if the area where your fuser is is kinda level. If not then you would have to pound them in to some degree.

RC

IM more likely to be in your boat in the middle of winter. It all depends on what the year holds. This is my first winter with a ton of LMB that I lucked out on. I think I have wayyyyy to many as a result of three bass I threw in here from a private pond. I also have a new aeration system and aerated all summer in the middle f the night. Fish are very active and the winter the pond WILL FREEZE but the snow depth can be like this at times if it snows hard enough.

Im reading all this but if I set my aerators at a shallow level when winter starts, the pond will rise significantly as its on an underground spring and run off. So the aerators will be deeper as the winter progresses.

I have a feeling I will have some LMB loss as my pond is getting low and there hundreds if not thousands of LMB in a small acre size pond that hits twice that size when it fills back up.

RUMBLON

This was a couple of springs ago, early spring. But typical. frozen solid during winter.

Any advice appreciated:
I manage an oval 3 acre pond (13 acre-ft volume), max depth 9ft, in lower New York State. There are some fish, but the pond is mostly used for swimming. Currently have 1hp aerator running four diffuser heads (6-9" long silica diffuser stones on each head). The intent is to minimize blue-green algae outbreaks during summer. My rough calcs show I turn over the lake volume more than 2/day. Now that winter is here, is there any benefit to continuing to run the aerator? I know that the temps are too low to promote bluegreen algae, but does winter aeration help, perhaps, promoting breakdown of the muck at the bottom of the pond?? Or am I doing more harm than good (by cooling the water column too much and stressing the fish) and should shut down for the winter?
Many thanks
Theodore

Generally there will be very little organic muck bacterial decomposition during winter water temperatures at 39F compared to the warm water seasons. Since a higher quality fishery is not a main goal for your pond, a mild winter kill will not be a dramatic event. Going into winter when water temperatures decrease to 50F most ponds naturally circulate top to bottom due to night cooling and increased wind action. At this point in many situations aeration can be turned off unless a specific need is present in the management plan or the goals.

What works for me is to turn off the two deep air stations and turn on the two shallow ones. The reason is to let the deeper water stay warmer and not cool the whole body of water. The shallow air stations is to keep the water open and if anyone or the dog falls into the water its shallow and close to shore to get out.

Cheers Don.